The sale price was not disclosed, but is believed to be about US$130 million.
The Stillman group will become the eighth owner of the Blues since the franchise came into existence in 1966. The group is buying the team from a group headed by Dave Checketts and his Sports Capital Partners Worldwide.
Stillman is chairman and chief executive officer of Summit Distributing in St. Louis and has owned a minority share in the Blues since 2007.
Spokesmen for the Blues and the NHL declined comment beyond a one-sentence news release from the league announcing approval of the sale. A news conference is expected on Thursday in St. Louis and may include commissioner Gary Bettman.
Other members of the group have not been announced. The $130 million price is well below the $157 million that Forbes had valued the Blues in December, which was 27th among the 30 NHL teams according to the magazine. It is also less than the $150 million price that the team sold for in 2006.
Stillman's group is getting what appears to be one of the up-and-coming teams in the NHL. After nearly a decade of struggles, the youthful Blues had the second-best record in the Western Conference this past season. They advanced to the second round of the playoffs before being swept by the Los Angeles Kings in four games in a series that ended Sunday.
Checketts announced two years ago that the team was going up for sale. Checketts and his group owned 20 per cent of the team, Towerbrook Capital Partners owned 70 per cent and Stillman 10 per cent.
Checketts, whose investment company also owns Real Salt Lake of Major League Soccer, had tried for months to put together a group of local investors to buy out Towerbrook but couldn't come to an agreement.
Note to readers: CORRECTS Kings eliminated Blues Sunday sted last week.Suggest a correction