| O'BRYAN'S CATTLE, INC. | DF027266 | 1988-04-07 | Inactive | — |
| O'CONNELL BROKERS LLC | DL215753 | 2021-12-06 | Dissolved | BOWDLE |
| O'CONNELL CONSTRUCTION, INC. | DB021487 | 1982-04-30 | Active | PHILIP |
| O'Connell Digital Ads LLC | DL175926 | 2020-01-16 | Dissolved | North Sioux City |
| O'Connell Enterprises, LLC | DL269532 | 2024-02-28 | Active | Beresford |
| O'Connell Farms, LLC | DL176382 | 2020-01-27 | Active | Beresford |
| O'CONNELL HOLDINGS, LLC | FL005428 | 2010-12-09 | Inactive | Houston |
| O'CONNELL LAW OFFICE, PROF. L.L.C. | DL030302 | 2012-12-03 | Inactive | SIOUX FALLS |
| O'CONNELL PARTNERS, LIMITED PARTNERSHIP | FP000773 | 2011-01-20 | Inactive | HOUSTON |
| O'Connell Properties, LLC | DL221535 | 2022-02-25 | Active | Aberdeen |
| O'CONNOR & SON TRUCKING, INC. | DB051035 | 2006-04-27 | Active | MITCHELL |
| O'CONNOR AND ASSOCIATES HEALTHCARE LLC | DL026348 | 2011-11-29 | Dissolved | MADISON |
| O'Connor Classical Education, LLC | DL145237 | 2018-03-12 | Inactive | Sioux Falls |
| O'CONNOR COMPANY | DB013205 | 1975-11-14 | Active | SIOUX FALLS |
| O'Connor concrete and excavation LLC | DL176386 | 2020-01-27 | Active | Yankton |
| O'Connor Construction and Woodworks LLC | DL219554 | 2022-01-31 | Active | Spearfish |
| O'CONNOR CONSTRUCTION LLC | DL003646 | 2001-03-23 | Active | HARRISBURG |
| O'CONNOR DRAIN TILE, LLC | DL024463 | 2011-04-21 | Active | BURBANK |
| O'Connor Enterprises, LLC | DL225150 | 2022-04-18 | Active | North Sioux City |
| O'CONNOR FARMS, LLC | DL018097 | 2009-01-15 | Active | MANKATO |
| O'Connor Holdings, LLC | DL139328 | 2017-11-02 | Dissolved | Dakota Dunes |
| O'CONNOR HOME IMPROVEMENT, INC. | DB025528 | 1986-06-27 | Inactive | — |
| O'Connor Jones: A People's Law Office, LLC | FL230093 | 2022-07-06 | Revoked | Boulder |
| O'CONNOR KILN AND DRYER, INC. | DB040605 | 1998-10-15 | Active | Vermillion |
| O'CONNOR LUMBER COMPANY INC. | DB001168 | 1960-08-27 | Dissolved | — |
| O'CONNOR MCMAHON, INC. | FB011749 | 1987-10-19 | Revoked | DALLAS |
| O'Connor of MA Corporation | FB239257 | 2022-11-28 | Active | canton |
| O'Connor P&B Farms, LLC | DL045099 | 2015-09-14 | Active | BURBANK |
| O'CONNOR PRODUCTIONS, INC. | DB006743 | 1952-12-15 | Dissolved | SIOUX FALLS |
| O'CONNOR PROPERTY MANAGEMENT L.L.C. | DL028061 | 2012-05-02 | Active | HARRISBURG |
| O'CONNOR REAL ESTATE ENTITY, L.L.C. | DL013690 | 2007-04-18 | Dissolved | FORT PIERRE |
| O'Daniel Construction, LLC | DL184069 | 2020-07-06 | Dissolved | Zell |
| O'Daniel Rentals, LLC | DL285776 | 2024-10-25 | Active | Athol |
| O'DANIEL TRUCKING, LLC | DL005444 | 2003-01-14 | Dissolved | ASHTON |
| O'Daniel Welding and Repair, LLC | DL285777 | 2024-10-25 | Active | Redfield |
| O'DAY EQUIPMENT, LLC | FL004236 | 2008-09-15 | Active | FARGO |
| O'DAY FAMILY LLC | DL167477 | 2019-07-17 | Dissolved | Sioux Falls |
| O'DAY INVESTMENTS, LLC | DL015907 | 2008-03-03 | Inactive | RAPID CITY |
| O'DAY MANAGEMENT, INC. | FB005655 | 1976-10-29 | Active | FARGO |
| O'DAY TANK & STEEL LLC | FL003648 | 2007-07-30 | Active | FARGO |
| O'Dea Livestock LLC | DL316193 | 2026-01-01 | Active | Philip |
| O'Dea Real Estate & Auction LLC | DL044297 | 2015-07-08 | Inactive | Philip |
| O'DELL CONSTRUCTION, INC. | FB032091 | 2007-10-19 | Inactive | SHERIDAN |
| O'DELL ELECTRIC, INC. | FB012942 | 1989-08-28 | Inactive | SOUTH SIOUX CITY |
| O'Dell Woodworks CO | DB174428 | 2019-12-16 | Dissolved | Rapid City |
| O'Donnell & Naccarato, Inc. | FB170040 | 2019-09-11 | Active | Philadelphia |
| O'Donnell Family Farm, LLC | DL138754 | 2017-10-20 | Active | Tulare |
| O'DONNELL, INC. | DB040769 | 1998-12-07 | Inactive | — |
| O'DONOVAN & ASSOCIATES, INC. | FB020703 | 1997-11-12 | Revoked | LAUREL |
| O'FARRELLS, INC. | DF005249 | 1965-12-27 | Dissolved | — |
| O'GORMAN HIGH SCHOOL | NS000193 | 1959-09-15 | Active | Sioux Falls |
| O'GRADY LLC | FL000997 | 2001-07-09 | Active | FARGO |
| O'GRADY-PEYTON INTERNATIONAL (USA), INC. | FB026076 | 2002-03-21 | Active | DALLAS |
| O'HALLORAN INTERNATIONAL, INC. | FB034912 | 2011-01-20 | Inactive | ALTOONA |
| O'HANLON LLC | DL006396 | 2003-10-16 | Active | Brandon |
| O'HARA GRAVEL, L.L.C. | DL026769 | 2012-01-05 | Dissolved | MADISON |
| O'HARA MASONRY, INC. | DB037310 | 1996-06-05 | Dissolved | RENNER |
| O'HARA PROPERTY LLC | DL011552 | 2006-06-15 | Dissolved | Montrose |
| O'HARA REALTY GROUP, INC. | DB056044 | 2011-03-28 | Dissolved | SIOUX FALLS |
| O'HARA REALTY LLC | DL008247 | 2004-11-29 | Dissolved | — |
| O'Hara Rentals LLC | DL240014 | 2022-12-08 | Dissolved | Sioux Falls |
| O'Hara's Painting and Cleaning LLC. | DL194438 | 2021-01-10 | Dissolved | Yankton |
| O'Heavens Catering Kitchen LLC | DL246964 | 2023-03-21 | Dissolved | Lake City |
| O'KANE FAMILY PROPERTIES L.L.C. | DL003830 | 2001-06-07 | Inactive | HUMBOLDT |
| O'Kane Law Office, LLC | DL285662 | 2024-10-23 | Dissolved | Sioux Falls |
| O'KAYES FURNITURE & APPLIANCE OF ORTONVILLE, INC. | FB281019 | 2024-08-14 | Active | Big Stone City |
| O'KEEFE DRILLING COMPANY, INC. | FB036080 | 2012-06-26 | Inactive | BUTTE |
| O'KEEFE DRILLING COMPANY, INC. | FB011164 | 1986-11-04 | Revoked | BUTTE |
| O'KEEFE ELEVATOR COMPANY, INC. | FB032228 | 2007-12-03 | Inactive | Atlanta |
| O'KEEFE ELEVATOR COMPANY, INC. | FB008274 | 1982-03-18 | Revoked | OMAHA |
| O'KEEFE IMPLEMENT, INC. | DB019295 | 1979-12-17 | Active | DE SMET |
| O'Keefe Millwork, LLC | FL288372 | 2024-12-06 | Active | RIVER FALLS |
| O'KEEFE, INC. | 19420001D | 1942-07-01 | Dissolved | — |
| O'Keeffe O'Brien Lyson Ltd. | FB143300 | 2018-01-30 | Active | FARGO |
| O'kief Properties LLC | DL242897 | 2023-01-24 | Active | Rapid City |
| O'LEARY BROS., INC. | DF016685 | 1979-05-11 | Active | TIMBER LAKE |
| O'Malley Construction LLC | DL166913 | 2019-07-03 | Dissolved | Centerville |
| O'MALLEY ENTERPRISES, INC. | DB009107 | 1968-12-10 | Inactive | — |
| O'MALLEY'S, INC. | DB041840 | 1999-09-16 | Dissolved | — |
| O'Neal Medical, LLC | DL042053 | 2015-01-23 | Dissolved | RAPID CITY |
| O'Neal Properties LLC | DL210185 | 2021-09-15 | Active | Dakota Dunes |
| O'Neal Vision Prof. LLC | DL173784 | 2019-12-03 | Active | Dakota Dunes |
| O'NEIL COMPANY, INCORPORATED | FB010887 | 1986-05-21 | Active | Williston |
| O'NEILL CATTLE COMPANY, INC. | DF036782 | 1996-01-30 | Active | CODY |
| O'NEILL CUSTOM CONCRETE, INC. | FB033596 | 2009-06-26 | Revoked | SIOUX CITY |
| O'NEILL FAMILY RANCH, LLC | DL029191 | 2012-08-23 | Active | HERMOSA |
| O'NEILL FARMS, INC. | DF036781 | 1996-01-30 | Dissolved | CODY |
| O'NEILL MARKETING LLC | FL275853 | 2024-05-28 | Active | Irvine |
| O'Neill Ops, LLC | DL040673 | 2014-10-14 | Active | TUTHILL |
| O'NEILL PIG, INC. | FB009717 | 1984-08-03 | Revoked | COLUMBUS |
| O'Neill Plaza II, LLC | DL213985 | 2021-11-08 | Active | Whitewood |
| O'NEILL PLAZA, L.L.C. | DL002028 | 1999-01-07 | Inactive | — |
| O'NEILL PLAZA, LLC | DL012137 | 2006-09-20 | Active | Whitewood |
| O'Neill Properties II, LLC | DL220892 | 2022-02-17 | Active | Clark |
| O'NEILL PROPERTIES, INC. | DB020488 | 1981-03-18 | Dissolved | — |
| O'NEILL PROPERTIES, LLC | DL034805 | 2013-08-20 | Active | CLARK |
| O'NEILL RANCH, LLC | DL018060 | 2009-01-09 | Inactive | RAPID CITY |
| O'Neill Rentals, LLC | DL149730 | 2018-06-15 | Active | Brookings |
| O'Neill Ventures, LLC | DL205553 | 2021-06-29 | Active | Tuthill |
| O'NEILL'S DRYWALL, INC. | DB050392 | 2005-12-12 | Active | Watertown |
| O'NEILL'S PUB, INC. | DB044076 | 2001-05-01 | Dissolved | HENRY |
| O'NEILL, L.L.C. | DL040785 | 2014-10-20 | Active | BROOKINGS |
| O'NEILL-ROEBUCK ENTERPRISES, INC. | DB030488 | 1991-04-01 | Inactive | — |
| O'REAR ASSOCIATES, L.L.C. | DL015800 | 2008-02-15 | Dissolved | Sioux City |
| O'REAR ENTERPRISES, INC. | DB053333 | 2008-02-25 | Dissolved | SIOUX CITY |
| O'REILLY AUTO ENTERPRISES, LLC | FL042333 | 2014-01-08 | Active | Springfield |
| O'REILLY AUTOMOTIVE STORES, INC. | FB029969 | 2005-09-15 | Active | Springfield |
| O'Reilly Properties LLC | DL324291 | 2026-03-25 | Active | Hendricks |
| O'ROURKE AGENCY, INC. | FB017125 | 1994-07-25 | Revoked | HOPKINS |
| O'Rourke Development, LLC | DL042208 | 2015-02-04 | Dissolved | MARTIN |
| O'Rourke Music Studios, LLC | DL185444 | 2020-08-03 | Active | Rapid City |
| O'ROURKE/BADLANDS ENTERPRISES L.L.C. | DL034940 | 2013-08-30 | Active | PORCUPINE |
| O'S GOLD SEED COMPANY | FB005679 | 1976-11-22 | Inactive | PARKERSBURG |
| O'Schipcon, LLC | DL164913 | 2019-05-20 | Active | Dakota Dunes |
| O'Shea Vocal Studio LLC | DL151258 | 2018-07-18 | Active | SPEARFISH |
| O'Toole Family, LLC | DL303765 | 2025-07-02 | Active | Tyler |
| O'TOOLE'S BAR, INC. | DB011247 | 1972-08-25 | Inactive | — |
| O'Town Enterprises, LLC | DL170114 | 2019-09-12 | Active | Onaka |
| O-5 Cattle Company, Inc. | DB153199 | 2018-08-29 | Active | MOBRIDGE |
| O-D, L.L.C. | DL000096 | 1994-01-28 | Dissolved | — |
| O-Line Fusion BBQ LLC | DL301757 | 2025-06-04 | Active | Sioux Falls |
| O. &. S., INC. | DB039191 | 1997-10-31 | Dissolved | — |
| O. DALE LARSON ENTERPRISES, INC. | DB010479 | 1971-02-26 | Inactive | — |
| O. F., L.L.C. | DL020577 | 2010-01-11 | Active | CODY |
| O. FIEBER, LLC | DL043781 | 2015-05-21 | Active | GOODWIN |
| O. GUNDERSON FARMS, INC. | DF012127 | 1974-01-31 | Inactive | — |
| O. K. CLIFFORD COMPANY | 19250011D | 1925-12-29 | Dissolved | — |
| O. L. BUSSMUS FARMS INCORPORATED | DF011685 | 1973-05-23 | Active | MITCHELL |
| O. R. B. Ltd | DB060743 | 2016-03-14 | Dissolved | STEAMBOAT SPRINGS |
| O. R. Clyne Law Office, LLC | DL248251 | 2023-04-06 | Inactive | Sioux Falls |
| O. W. HOLMES INC. | 19660179D | 1966-03-24 | Active | — |
| O.A. HENDERSON ENTERPRISES, INC. | DB045247 | 2002-03-21 | Inactive | — |
| O.A.S.I.S. Profit Models, LLC | DL278649 | 2024-07-11 | Dissolved | Sioux Falls |
| O.C. CLEANERS, INC. | DB043381 | 2000-11-02 | Dissolved | SPEARFISH |
| O.C. ENTERPRISES, LLC | DL167117 | 2019-07-10 | Active | FORT PIERRE |
| O.C., INC. (RAPID CITY) | DB022718 | 1983-09-14 | Inactive | — |
| O.C.S., LLC | DL030611 | 2012-12-18 | Inactive | BRITTON |
| O.D.I.N. ALLIANCE INC. | DB061209 | 2016-11-07 | Dissolved | MAYFIELD |
| O.E.S., INC. | FB008966 | 1983-05-26 | Revoked | WINDOM |
| O.F. DRAGOO SODHOUSE CORPORATION | NS009489 | 1991-10-07 | Inactive | — |
| O.F.P. ENTERPRISES, L.L.P. | DR000324 | 1998-12-16 | Dissolved | ABERDEEN |
| O.I.A. INC. | FB024741 | 2001-01-17 | Revoked | ROCHESTER |
| O.I.A. INC. | FB018321 | 1995-10-11 | Revoked | ROCHESTER |
| O.J.'S EGGS, INC. | DB029616 | 1990-06-22 | Inactive | — |
| O.J., INC. | DB025777 | 1986-10-16 | Inactive | — |
| O.K. AUTO PARTS & EQUIPMENT, INC. | FB018471 | 1995-12-11 | Revoked | MINOT |
| O.K. FREIGHTWAYS, INC. | FB015180 | 1992-04-06 | Revoked | ST PAUL |
| O.K. ORDER BUYERS, INC. | DB012801 | 1975-03-13 | Inactive | — |
| O.L. BUSSMUS CONSTRUCTION INC. | DB036678 | 1996-01-04 | Active | MITCHELL |
| O.M. ABERDEEN, LLC D/B/A O.M.A., LLC | FL000415 | 1998-12-02 | Revoked | BALLWIN |
| O.N.L.E. Ministries | NS256558 | 2023-08-13 | Dissolved | Spearfish |
| O.P.C., INC. | DB028031 | 1989-01-09 | Inactive | — |
| O.P.E.N. AMERICA, INC. | FB035300 | 2011-07-22 | Active | PHOENIX |
| O.R. 7, Inc. | DB059593 | 2014-12-02 | Dissolved | MIRCHELL |
| O.R. ASSOCIATES, INC. | DB036507 | 1995-12-07 | Dissolved | SIOUX FALLS |
| O.R. COLAN ASSOCIATES OF ILLINOIS, LLC | FL002854 | 2006-03-10 | Inactive | CHARLOTTE |
| O.R. COLAN ASSOCIATES, LLC | FL043887 | 2015-11-03 | Active | CHARLOTTE |
| O.R. SECURITIES, INC. | FB010526 | 1985-10-31 | Revoked | CHESTERFIELD |
| O.R.E.O., LLC | DL008634 | 2005-02-07 | Active | SIOUX FALLS |
| O.V.W.S.D., INC. | DB022572 | 1983-07-11 | Inactive | — |
| O.W. & B.S. LOOK, CO., INC. | 19630125D | 1963-06-12 | Active | — |
| O.W.N.S. INCORPORATED | DB056386 | 2011-10-12 | Dissolved | WATERTOWN |
| O.W.R. INVESTMENTS, LLC | DL012027 | 2006-08-31 | Active | Kimball |
| O.W.R. Land LLC | DL047066 | 2016-02-12 | Active | KIMBALL |
| O/C TANKS CORPORATION | FB012516 | 1988-12-27 | Inactive | TOLEDO |
| O2 Dynamics Ltd | DB058063 | 2013-09-16 | Dissolved | Luverne |
| O2 Landscapes, LLC | DL204469 | 2021-06-10 | Active | RAPID CITY |
| O2 Properties LLC | DL143295 | 2018-02-08 | Dissolved | Dakota Dunes |
| O2 Ventures LLC | DL312635 | 2025-10-30 | Active | Fort Pierre |
| O2B Early Education Holding, Inc. | FB299992 | 2025-05-10 | Active | Gainesville |
| O3 RANCH, L.L.C. | DL018008 | 2008-12-31 | Active | RAPID CITY |
| OA Athena Holdco Inc. | DB290656 | 2025-01-08 | Dissolved | Watertown |
| OA INC. | FB009583 | 1984-05-22 | Inactive | ENGLEWOOD |
| OA Ministries | NS207149 | 2021-07-26 | Active | Custer |
| OAC Industries, Inc. | DB190607 | 2020-11-03 | Active | Black Hawk |
| OAC Marketing, LLC | DL237391 | 2022-10-26 | Dissolved | Isabel |
| OACOMA CHAMBER OF COMMERCE | NS007039 | 1980-12-01 | Inactive | — |
| Oacoma Chamberlain Pukwana Area Community Foundation | NS296377 | 2025-03-25 | Active | Chamberlain |
| OACOMA HOUSING, INC. | DB010195 | 1970-07-15 | Dissolved | — |
| OACOMA SUPERMARKET, INC. | DB060368 | 2015-09-24 | Dissolved | MADISON |
| OAE Farms, LLC | DL288337 | 2024-12-05 | Active | Milbank |
| OAE Software, LLC | FL216980 | 2021-12-22 | Inactive | Boston |
| OAFS LLC | DL265267 | 2024-01-01 | Active | Agency Village |
| OAGT LLC | DL308258 | 2025-09-02 | Active | Sioux Falls |
| OAHE A.B.A.T.E. | NS011353 | 1999-09-29 | Dissolved | Pierre |
| Oahe Acres North Road District | TD148725 | 2018-05-24 | Active | — |
| OAHE AG SERVICES, INC. | DB030099 | 1990-12-27 | Dissolved | FORT PIERRE |
| Oahe Anesthesia Solutions PLLC | DL244984 | 2023-02-22 | Active | Rapid City |
| OAHE AREA RECREATION AND LEARNING CENTER | NS008562 | 1987-06-24 | Inactive | — |
| OAHE AREA YOUTH CENTER, INCORPORATED | NS010938 | 1997-12-19 | Inactive | — |
| OAHE ASSOCIATION OF SOUTHERN BAPTISTS | NS008818 | 1988-09-30 | Dissolved | — |
| Oahe Audio and Installations L.L.C. | DL047932 | 2016-04-08 | Dissolved | PIERRE |
| OAHE AUTO REPAIR, INC. | DB059088 | 2014-05-19 | Dissolved | PIERRE |
| Oahe Basketball Association, Inc. | NS235497 | 2022-09-27 | Active | Pierre |
| OAHE BOWMEN, INC. | NS010505 | 1996-02-22 | Active | Glenham |
| OAHE BUILDERS LLC | DL028812 | 2012-07-13 | Active | MOBRIDGE |
| OAHE CAR WASH, LLC | DL029689 | 2012-10-12 | Active | MOBRIDGE |
| OAHE CHAPEL PRESERVATION SOCIETY | NS008012 | 1985-01-15 | Active | PIERRE |
| OAHE CHAPTER #18 DISABLED AMERICAN VETERANS, DEPARTMENT OF SOUTH DAKOTA | NS008563 | 1987-06-25 | Active | PIERRE |
| OAHE CHAPTER, EXPERIMENTAL AIRCRAFT ASSOCIATION, NO. 848 | NS008137 | 1985-06-27 | Inactive | — |