Jeremy Menez's 53rd-minute strike was enough to end the capital club's long wait to reclaim the French crown and seal a first title since their big-spending Qatari owners took charge.
PSG's title will not, however, be confirmed until a league disciplinary panel meets to decide whether to impose a points deduction following allegations sporting director Leonardo barged a referee.
The Brazilian will front a hearing before the end of the season after he was charged for an incident that took place in the tunnel after PSG's 1-1 draw with Valenciennes at the Parc des Princes last weekend.
Reports have suggested PSG could be handed a two-point ban, with the club now seven points clear of nearest-rivals Marseille with two games to play.
Leonardo was handed a preliminary sanction in midweek which prevented him from joining the PSG staff on the touchline or in the dressing room at Stade Gerland on Sunday.
A healthy travelling support did make the trip to Lyon and after a nervy first half the match was decided by Menez.
Thiago Motta won the ball in midfield and after playing a one-two with Zlatan Ibrahimovic down the right he picked out Menez to fire in a low angled shot.
The final whistle sparked celebrations from the away side and boss Carlo Ancelotti, who has now masterminded domestic titles in his native Italy, England and France.
Ancelotti, who has been linked with a move away from PSG in the summer, also led the club to the quarter-finals of the Champions League this season before they were knocked out by Barcelona on away gaols.