Welbeck scores late winner for Gunners
The Gunners needed a victory in this game to cut Leicester City's five-point lead and they started brightly.
Arsene Wenger's men saw much of the ball while Leicester City were looking to break from the counter. The Gunners however could not fashion out a clear-cut chance.
Leicester City got the first real chance of the game as Jamie Vardy forced Petr Cech to a save from his header at the near post.
Cech was also alert to tip over a N'Golo Kanté curled strike as Leicester threatened on the break.
The Fox got their goal through a penalty which was given after Nacho Monreal fouled Vardy in the 18-yard box.
Liecester City's hit man, Vardy picked himself up to score in the 45th minute.
With Leicester down to 10 men -after defender Danny Simpson was sent off early in the second half, Arsenal pressed for a goal.
They Arsenal equalised after 70 minutes when substitute Theo Walcott scored from close range after Oliver Giroud's header found him in space.
The Gunners searched for the winner and missed many chances as Leicester City goalkeeper Kasper Schmeichel saved from Giroud and Alexis Sanchez.
He however could not keep out Welbeck's header from a Mesut Ozil freekick.
Welbeck, who had not played since last April, came on after 83 minutes and scored in the fifth minute of stoppage time to secure the victory.