Bayal Sall cancelled out Dodo's opener as Saint-Etienne hauled themselves level on points with Dnipro and Qarabag, four points behind Group F leaders Inter.
Inter took a deserved 33rd-minute lead in Thursday's game thanks to Dodo's cushioned finish. It was the Brazilian's second goal in his last four European appearances, Inter's first goal in open play in five games in all competitions and the first Saint-Etienne have conceded in the group stage.
However, Bayal Sall stabbed home a loose ball 10 minutes into the second half for his first goal in almost a year to earn Saint-Etienne, who dominated the second half and are now unbeaten in five games it all competitions, a decisive draw.
A seven-game goal drought cost Ricky van Wolfswinkel his place in Christophe Galtier's starting XI, while Inter counter Walter Mazzarri rested key players Samir Handanovic, Andrea Ranocchia and Mauro Icardi and included Juan Carrizo, Marco Andreolli and 17-year-old Federico Bonazzoli
Inter had the first chance after five minutes. Dodo's pass into the hosts' penalty area looked to be running out for a goal kick, but the sliding Bonazzoli's outstretched leg cut it back towards Zdravko Kuzmanovic, who failed to keep his effort on target from close range.
Rodrigo Palacio then intercepted an under hit back-pass, but in taking it round goalkeeper Stephane Ruffier, allowed two defenders to get back and found himself at an acute angle. Bayal Sall passed Palacio's tame shot to Ruffier, who pounced on it rather than blasting it clear.
An indirect free-kick was awarded that was rolled to Mateo Kovacic six yards out. The Croatia international thumped it goalwards, but, after it cannoned off the post and into a defender, Saint-Etienne managed to thump it away.
Ruffier then caught a firm Ibrahima Mbaye header on his line before repelling a rasping Kuzmanovic effort.
Romain Hamouma finally produced Saint Etienne's first attempt after 25 minutes, cutting inside Marco Andreolli from the left before firing straight at Juan Carrizo.
It was merely brief respite for the hosts, however, and Inter finally made them pay 12 minutes before the break.
Palacio's header from a right-wing cross was parried by Ruffier, but the rebound fell to Dodo. The 22-year-old Brazilian still had work to do, but his cushioned volley from a tight angle went just inside the post.
Galtier's half-time team-talk seemingly reinvigorated Saint-Etienne and they swiftly equalised.
When Nemanja Vidic failed to clear a corner, Bayal Sall was quickest to react to the loose ball, firing past Carrizo from eight yards.
Saint-Etienne continued to take the game to Inter, with Palacio deflecting a goal-bound Hamouma drive over his crossbar and Kevin Theophile-Catherine forcing Carrizo to make a low save.
Substitute Van Wolfswinkel's quick footwork got him away from Vidic and clean through on goal after 85 minutes, but his close-range shot was saved by Carrizo, who did well to make himself big.
That proved the last opportunity of a game of two halves, leaving Inter on the verge of the last 32.
