Lille claimed their first French league title since 1954 despite being held to a 2-2 draw at French Cup final victims Paris Saint-Germain in a heated encounter here on Saturday.
Victors over PSG in last weekend's Cup showdown, Lille required just a point to complete the second league and cup double in their history and they procured it despite Mathieu Bodmer's 73nd-minute equaliser for the hosts.
Moussa Sow had put Lille ahead 14 minutes earlier, after PSG striker Guillaume Hoarau and coach Antoine Kombouare had both been dismissed to the sound of whistles raining down from the Parc des Princes tribunes.
Lille's players rushed to celebrate with the away fans at the final whistle, although second-placed Marseille's 2-2 draw at home to Valenciennes meant they would have been assured of the title even in case of defeat.
Lyon's 0-0 draw with Caen, meanwhile, means PSG will go into their final game of the season at Saint-Etienne with a chance of pipping OL to a Champions League place.
Gregory Coupet's hopes of keeping a clean sheet on his final appearance at Parc des Princes for PSG were dashed inside five minutes as his French Cup final nemesis Ludovic Obraniak put the visitors ahead.
It was a 90th-minute free-kick by Obraniak that embarrassed Coupet and gave Lille the cup at Stade de France, and the Polish winger was just as unerring with a low drive from the edge of the box that beat Coupet to his left.
PSG took the other hand thereafter, with Hoarau flashing an overhead bicycle kick millimetres wide and Ludovic Giuly hitting the crossbar, before the hosts levelled in controversial circumstances in first-half injury time.
With the visitors mistakenly believing referee Lionel Jaffredo had blown the half-time whistle, Nene took a quick free-kick from which Hoarau slammed home the equaliser.
It provoked a furious reaction from Lille coach Rudi Garcia, and his players, who were further aggrieved by the fact two PSG players were in offside positions.
The tables quickly turned in the second half, however, with Hoarau sent off inside 20 seconds after being shown a second yellow card for a dive inside the Lille penalty area.
PSG's mounting frustration saw Kombouare almost come to blows with the fourth official and after he was sent to the stands, Sow slid in to convert Mathieu Debuchy's low cross and claim his 22nd goal of the season.
Despite being a man down PSG continued to press and after Giuly had rolled a low shot against the far post, Bodmer thumped home a tremendous equaliser via the underside of the crossbar to crown a game of fierce intensity.