All four goals came in the final half hour of a game that left third-place and defending champion Chelsea 16 points behind Manchester City and Arsenal 23 adrift of the leaders.
The deficit would have been even worse for the sixth-place hosts had Bellerin not redeemed himself. The right back's challenge on Eden Hazard had allowed the Chelsea winger to cancel out Jack Wilshere's opener in the 67th minute.
Marcos Alonso fired Chelsea in front in the 84th with his sixth goal of the season, but wasn't as meticulous back on defensive duties in the second minute of stoppage time. A headed clearance went straight to Bellerin, who leveled with a half-volley.
Chelsea was still pursuing the winner in the third minute of stoppage time when defender Davide Zappacosta struck the crossbar.
Had striker Alvaro Morata not missed so many chances this could have been a third consecutive win for Chelsea. Chelsea is becoming reliant on Alonso for goals, with the left-sided defender the team's second-highest scorer behind Morata.
On the night when Diego Costa scored on his return to Atletico Madrid from Chelsea, the ferocious forward seems just what the champions have required at times.
Instead all Chelsea and Arsenal can realistically now achieve through the league is Champions League qualification. Even that could be beyond Arsene Wenger's side, with fourth place five points away.
Fortune wasn't on Arsenal's side against Chelsea.
Alexis Sanchez managed to hit both posts in the 16th - with the ball pinging from one side of the goal to the other without crossing the line. Then Chelsea goalkeeper Thibaut Courtois blocked Alexandre Lacazette's low shot on the turn.
After Hazard and Alonso were denied by Petr Cech at the start of the second half, Courtois used his sprawling body to again thwart Lacazette.
Wilshere, who had been booked in the first half for a challenge on former Arsenal teammate Cesc Fabregas, was fortunate to avoid a second yellow card for diving just before scoring.
Wilshere stayed on the pitch and lit up the game by combining with Mesut Ozil before scoring an eye-catching goal, slamming a fierce shot off the left hand post and into the net. In an Arsenal career punctuated by injuries and a season on loan at Bournemouth, it was Wilshere's first league goal since May 2015.
Wilshere's good work was undone when Bellerin's high challenge on Hazard led to the equalizer from the spot.
''He's always very quick in the box,'' Bellerin said. ''I saw the ball in the air and I tried to challenge for it. We both went for the ball at the same time.''
Wenger was less diplomatic, calling it a farcical penalty.
''At the moment we have to face surprising decisions,'' Wenger said.
Cech was beaten again when Willian's cross-field pass reached Zappacosta on the right flank and a cross was aimed at Alonso, who got ahead of Shkodran Mustafi to turn the ball into the net.
But Bellerin still found time for his first league goal since last season.
''I'm happy with the goal but also happy with the reaction at the end of the game,'' he said. ''It's non-stop football. We know whenever we play them it's always a hard game, there's always a lot of entertainment, always really hard, we work hard all week.''
This version corrects the standings in the second paragraph and summary.