OSB was formed in 2014, as a partnership between the two offshore wind foundation firms, taking over the Tag Energy Solutions fabrication yard in Teesside, north-east England.
The move, "made in joint and mutual understanding", was agreed "as part of an overall settlement of several outstanding commercial issues", according to Bladt Industries.
Following the takeover, OSB will be renamed EEW Offshore Structures Britain.
EEW chief executive Heiko Mützelburg said:"We also see great potential for the future in the British offshore wind market sector and, of course, we would like to support local content in the UK."
To-date, OSB has mostly supplied transition pieces to offshore wind projects in the UK, including an expanded deal announced this week with Ørsted (formerly Dong Energy) for its Hornsea Project One site.
Bladt Industries CEO Jan Kjaersgaard, added: "We are very happy to have contributed our expertise to having successfully established a UK-based operation serving local projects.
"We have decided to sell our shares and focus on applying our vast industry and UK competences on serving the UK offshore wind market in alternative ways. We are very pleased with the overall agreement and its financial implications for Bladt Industries."