| Baltic Naval Solutions Ab | Professional & scientific | 2017 |
| Baltic Resources Ab | Professional & scientific | 2003 |
| Baltic Trading Company Ab | Wholesale & retail | 1977 |
| Bara Klippning Ab | Other services | 2019 |
| Baron's Food Alandia Ab | Wholesale & retail | 2004 |
| Beauty Hair & Make Up Studio Ab | Other services | 2001 |
| Bedris Måleri & Bygg Ab | Construction | 2015 |
| Begravningsbyrå Nocturne Ab | Other services | 2011 |
| Bellac Ab | Information & communication | 1998 |
| Bengt Dahlgren Stockholm Aktiebolag, filial Åland | Professional & scientific | 2020 |
| Bengt Granholm Ab | Wholesale & retail | 1983 |
| Bently Invest Ab | Financial services | 2026 |
| Bergö Lax, öppet bolag | Agriculture & fishing | 1986 |
| Berhen Group AB | Information & communication | 2020 |
| Berndt Schalin Board Advisors Oy | Professional & scientific | 2006 |
| Bertel Wickström & Co Ab | Wholesale & retail | 1981 |
| Berthén Mare Marin Ab | Transport & logistics | 2012 |
| Beshi Dental Ab | Health & social care | 2021 |
| Bifa Ab Bilfirma | Wholesale & retail | 2008 |
| Bikini Tours Ab | Administrative & support | 2025 |
| Bilmo Ab | Information & communication | 2026 |
| Bilservice Åland Ab | Other services | 2025 |
| Biltema Real Estate Åland Ab | Real estate | 2018 |
| Bilverkstan i Mariehamn Ab | Other services | 2016 |
| Bimelix Ab | Health & social care | 2009 |
| Björkkö Ab | Health & social care | 2017 |
| Björkmans Plåtslageri Ab | Construction | 2020 |
| Björlin GITech Ab | Professional & scientific | 2012 |
| Björn ide Ab | Information & communication | 2009 |
| BlackEye Capital Ab | Professional & scientific | 2008 |
| Blindfors Ab | Health & social care | 2024 |
| Bo Cap Ab | Wholesale & retail | 1920 |
| Bo-Bil Ab Mariehamn | Wholesale & retail | 1968 |
| Bobiten Ab | Real estate | 2011 |
| Bokföringsbyrå Da-Ka, öppet bolag | Professional & scientific | 1994 |
| Boland kiinteistöt Oy | Real estate | 2016 |
| Boman & Sundberg Ab | Wholesale & retail | 2006 |
| Bomans Trafikskola Ab | Education | 2019 |
| Bomanson & Co Ab | Construction | 2019 |
| Bomanson Fastigheter Ab | Real estate | 2019 |
| Bomanson Holding Ab | Financial services | 2019 |
| BoostCo Oy | Education | 2021 |
| Bra Fastigheter i Svibydal Ab | Real estate | 1979 |
| Bra Möbler på Åland Ab | Wholesale & retail | 2004 |
| Brainvest AB | Professional & scientific | 2019 |
| Brell AB | Transport & logistics | 2020 |
| Brink Tec Ab | Professional & scientific | 2015 |
| Brudhäll Ab | Hospitality | 1987 |
| Bruson Invest Ab | Real estate | 1987 |
| Bryggan Fastigheter Aktiebolag | Real estate | 2010 |
| Brändötrafiken AB | Transport & logistics | 2021 |
| Butikslokal Skarpans Ab | Real estate | 2001 |
| Butterhill Ab | Financial services | 2023 |
| By Julietta Ab | Other services | 2013 |
| Bygg & Måleri Pekka Niemi Ab | Construction | 1994 |
| Bygg & Måleri R. Karlsson Ab | Construction | 2009 |
| Byggerål Ab | Real estate | 1978 |
| Byggfast Ab | Construction | 2011 |
| Byggfirma Christer Gustavsson Ab | Construction | 2000 |
| Bygghm ab | Construction | 2021 |
| Byggkontroll Åland Ab | Construction | 2008 |
| Bygglovet på Åland Ab | Real estate | 2017 |
| Byggnadsfirma Hans Mattsson Ab | Construction | 1981 |
| Byggpartner Åland Ab | Construction | 2021 |
| Byggträ, U. Simons Ab | Wholesale & retail | 1974 |
| ByteJot AB | Information & communication | 2024 |
| Bäck Advokatbyrå Ab - Bäck Asianajotoimisto Oy | Professional & scientific | 2019 |
| Bärgarn Ab | Transport & logistics | 2008 |
| C THEOX LTD, Suomen sivuliike | Construction | 2024 |
| CB Invest Group Oy | Administrative & support | 2025 |
| CB Konstruktion Ab | Real estate | 2016 |
| CL Education Ab | Health & social care | 2018 |
| CL Fastigheter Ab | Real estate | 2018 |
| CL Group Ab | Financial services | 2018 |
| CL Invest Ab | Financial services | 2012 |
| CLT Åland Ab | Construction | 2021 |
| CONNY HENRIX Ab | Arts & recreation | 2023 |
| CR Affärskonsult Ab | Professional & scientific | 2017 |
| CV Nikulas Kompetens AB | Administrative & support | 2015 |
| CW Golf Ab | Wholesale & retail | 2005 |
| Caelum Oy | Financial services | 1991 |
| Cainby Ab | Manufacturing | 2006 |
| Calle & Co Ab | Wholesale & retail | 1997 |
| Calliflow Ab | Wholesale & retail | 2019 |
| Canard Ab | Professional & scientific | 2015 |
| Carelian Caviar Marketing Ab | Wholesale & retail | 2016 |
| Carl Oscar Dannströms Aktiebolag | Professional & scientific | 2015 |
| Carl Rundberg Ab | Real estate | 2016 |
| Carus Ab Ltd | Information & communication | 2007 |
| Carus Ferry Ab Ltd | Information & communication | 1987 |
| Carusl-PBS Invest Ab | Financial services | 2015 |
| Casperian Ab | Financial services | 2024 |
| Cavannus Ab | Information & communication | 2020 |
| Cegeland Ab | Financial services | 2026 |
| Centrum i Mariehamn Ab | Real estate | 2016 |
| Chibo Holdings Ab Ltd | Financial services | 2016 |
| Chili Ink Ab | Other services | 2014 |
| Chilibolaget Ab | Manufacturing | 2020 |
| Christians Ekotjänster Ab | Professional & scientific | 2024 |
| Ciceron Data Ab | Information & communication | 2008 |