A deflected strike from Lyon's Cameroon international Clinton N'Jie with 13 minutes remaining at Stade du Moustoir cancelled out Jordan Ayew's second-half opener.
The result - the third straight draw between the two teams at Lorient - left Lyon two points clear of Marseille and defending champions Paris Saint-Germain after 25 matches.
Lyon came into the fixture on the back of consecutive draws against Monaco and PSG, but Hubert Fournier's men were expected to see off the challenge of Lorient, who hover just two points above the relegation zone.
Ayew, who replaced Rafidine Abdullah at the break, tapped home the opener from Benjamin Jeannot's cross.
Lyon went in search of an equaliser and were rewarded in the 77th minute, with N'Jie firing the ball underneath Lorient goalkeeper Benjamin Lecomte, who was unable to keep it out.
Meanwhile, Guingamp defeated rock-bottom Metz 2-0 away from home at Stade Saint-Symphorien.
