The 31-year-old has agreed a two-year deal at The City Ground after being freed by Everton at the end of the season.
"There was interest from Leeds and Ipswich but I just felt that joining Forest was the right thing to do," said Gerrard - who enjoyed a loan spell at Forest earlier in the year.
"I really enjoyed my loan spell at The City Ground last season. There's a nice feel about the club, a good staff and I was made to feel really welcome by the supporters, which is important.
"I discussed all my options with my wife and family over the summer and came to the conclusion that joining Forest was the best move."
