Brighton scored a late goal to earn one point after Leicester had come from behind to take the lead at King Power Stadium.
Kaoru Mitoma opened the scoring for Brighton after he drifted into the midfield and swept in a stunning curled shot from outside the area for his fourth goal in six games.
Leicester’s Marc Albrighton tucked past Brighton goalkeeper, Robert Sanchez, for the equaliser.
Barnes put the home side ahead when he confidently finished Luke Thomas’ header, flicked on from a corner, and for 25 second-half minutes Brendan Rodgers’ men looked like they would earn their first win in five games.
However, 18-year-old Ferguson rescued a point for Brighton with his third Premier League goal, when he met Pervis Estupinan’s cross to head into the far corner.
The result moves Brighton up to sixth in the league while the Foxes are 14th but just one point above the relegation places.