The midfielder broke the deadlock in the 81st minute as the Royals eventually overcame a dogged Forest side to spark wild celebrations at the Madejski Stadium.
The goal came minutes after news filtered through that nearest challengers West Ham had been held to a 1-1 draw by Bristol City at Ashton Gate.
Forest, though, came close to snatching a point and putting the champagne on ice but substitute Marcus Tudgay's header was cleared off the line by Alex Pearce with the striker's follow-up effort being kept out by Adam Federici deep into injury time.
It was Reading's sixth successive win, eighth in a row at home and their 15th in the last 17 games, form which has seen them leapfrog long-time leaders Southampton at the summit.
Despite the defeat, only their second in eight games, Forest secured Championship football for another season with Coventry losing at home to Millwall.