The 24-year-old midfielder, who began his career at Middlesbrough and spent two seasons at Stockport before returning to the North East with The Quakers four years ago, has signed a three-year contract at Spotland.
The player insisted it was his decision to leave David Hodgson`s side after last season`s Third Division play-off final defeat and believes he has moved to a club with more long-term potential.
"In was offered another year at Darlington," Oliver said. "I think the ambition`s gone out of them."
"With them not going up last year automatically, and then the disappointment of the play-offs.
"The chairman up there has cut the wage bill and that was the main reason I left because they couldn`t afford to keep me.
"It`s a new beginning for me at Rochdale and I`m delighted to be here.
"I could have gone to Hartlepool and there were one or two other offers but they were just too close to home and it was time for a change."
