The forward came off the bench 10 times but failed to find the net, but impressed O'Driscoll enough to earn a 12-month contract at the Keepmoat Stadium.
"He's one for the future. He's a couple of years away from being the finished article, but he's got a presence about him," O'Driscoll told the club's official website.
"He's six foot, aggressive and can replace Mark McCammon, who gave us that last season.
"Tomi's 19 and he's one we think that, if we treat him right, we could develop him."