Freiburg, Germany – Last-place Freiburg fired manager Marcus 14 season.
Sorg, 46, took over in July for Rubin Dutt, who left to become coach at Bayer Leverkusen. But the former Freiburg youth coach had little success as Freiburg accumulated just 13 points in 17 Bundesliga games in the season's first half.
Streich, 46, has been on the coaching staff since 1995, and will have to lift the club off the bottom of the table.
"We're absolutely convinced," Freiburg sporting director Dirk Dufner said, "this is the right solution."
Freiburg finished ninth in the Bundesliga last season, but in addition to the firing of Sorg, terminated midfielder Yacine Abdessadki's contract and added five other players, including captain Heiko Butscher, to the transfer list.
"We have a lively team and if we can tighten up a few things and close the gaps at the back, then we can achieve our aim, which is to avoid relegation," said Streich.
The Bundesliga returns from winter break on Jan. 20 when Bayern Munich visits Monchengladbach, and Streich will debut the following day when Freiburg hosts Augsburg.