The 24-year old joined the Merseyside outfit in the summer transfer window on loan from Real Madrid but failed to make a significant impact at the club, making just 12 appearances under Brendan Rodgers.
Sahin, however, claims that his time in the Premier League was worthwhile due to the experience he gained from playing alongside Steven Gerrard. He believes the England international has helped him improve his all-round midfield game.
"I have matured as a player after playing alongside the best players in my position," Sahin told the club's official website.
"Xabi Alonso when I was at Real Madrid, but especially Steven Gerrard at Liverpool - even though I didn't get to play a lot with him."
Sahin is on his second spell at the German club after coming through the youth team before departing to Spain in 2011.
He was a crucial member of the side which dethroned Bayern Munich to win Dortmund's first Bundesliga title in almost a decade, becoming the Bundesliga's Player of the Season in 2010/2011.
The loan deal will see the Sahin, still a Real Madrid player, stay with Jurgen Klopp's side until the end of the season.