Scotland was out of contract at the end of last season but has secured an extended stay at Portman Road.
The 33-year-old joined the Tractor Boys from Wigan in August 2010 and has netted 19 goals in 81 appearances.
"There was never any doubt that Jason was going to stay," said boss Paul Jewell on the club's official website. "He had a few issues that he needed to sort out and he's done that and we're pleased to have him around the place again. He certainly adds to the noise!
"He knows he's not going to start and finish every game but what he showed last season is that he can have an impact on matches.
"He's a great character to have in the dressing room and he will have an important part to play for us next season whether it's coming off the bench or playing the first hour or so."