
The hosts, who only narrowly avoided relegation last term, are now four points clear of Saint-Étienne after applying a modicum of pressure on champions PSG, who defend their 100% record against Lyon on Sunday.
Bamba got Lille off to a flying start in the 17th minute, collecting Loïc Rémy’s lay-off before creating space for a shot which flew into the bottom corner.
Rémy Cabella levelled for Saint-Étienne from the penalty spot just nine minutes later, but Bamba struck again in the opening minute of the second half.
Nicolas Pépé sent the 22-year-old racing clear, and he cut inside before curling home another unerring finish from the edge of the box.
Bamba, who left Saint-Étienne for Lille on a free transfer in the off-season, has now scored seven goals in only nine appearances for his new club.
A fourth win in five matches was wrapped up late on, as Bamba broke away from the visitors’ midfield and slipped through a pass for Pépé to fire between the legs of Les Verts goalkeeper Stéphane Ruffier.
Pépé, 23, has thus far netted six goals this season.