Alvaro Arbeloa’s Madrid seemed set to chop down Barca’s lead but the Catalans sit provisionally eight points ahead of Madrid after Bellerin cancelled out Vinicius Junior’s opener.
Hansi Flick’s defending champions, shorn of injured teenage winger Lamine Yamal, visit Getafe on Saturday and now have the chance to move 11 points clear of Los Blancos with a victory.
Vinicius’s 17th-minute strike seemed set to bring his team victory and boost their slim chances of overhauling the leaders and finishing the season with a trophy.
However, Madrid were rocked in stoppage time as Bellerin finally provided the breakthrough his side’s performance had deserved.
“We suffered another blow in the final minutes, as has already happened to us many other times, and we end up with a result I don’t think we deserved, because we had chances (to win),” Arbeloa told reporters.
The Madrid coach complained about refereeing decisions which “heavily influenced the game”, although Betis arguably had the more legitimate grievances.
The hosts, fifth, appealed in vain for a penalty against Brahim Diaz early on, after the Madrid midfielder appeared to touch the ball with his hand in his own box as he tried to control it.
A few minutes later the visitors took the lead, when Betis goalkeeper Alvaro Valles could only push Federico Valverde’s drive back into Vinicius’s path and the Brazilian swept home.
England international Jude Bellingham almost doubled Madrid’s advantage but Valles did well to tip over his fierce effort.
Betis push on
Betis earned a foothold in the game and Madrid had their goalkeeper Andriy Lunin, playing in place of the injured Thibaut Courtois, to thank for getting them in ahead at half-time.
Lunin pushed Antony’s low strike around the post and then denied the Brazilian winger again, having just thwarted Cedric Bakambu as he ran through on goal.
Alvaro Fidalgo also lashed narrowly over as Betis pushed Madrid back, albeit without finding a way through.
On an otherwise quiet night for the league’s top goalscorer, Madrid striker Kylian Mbappe polished off Trent Alexander-Arnold’s cross early in the second half but his goal was chalked off for offside.
Lunin was soon the hero again for Madrid as he pushed Cucho Hernandez’s powerful effort over and defender Dean Huijsen blocked well from Antony.
The former Manchester United winger was Betis’s biggest threat and he hit the deck in the area towards the end, saying he was blocked by Ferland Mendy’s arm, although no penalty was forthcoming.
Madrid forward Mbappe appeared to ask for a substitution with 10 minutes remaining, creating worry over a possible injury for the French striker ahead of the World Cup.
Betis snatched a point right at the death, with Bellerin in the right place at the right time to smash home a loose ball in the area after Antonio Rudiger blocked a cross.
“In these situations you have very little time to think,” Bellerin told DAZN of his goal.
“We had a lot of chances, during the game I had the feeling that we had a lot of control and we were getting opportunities and we didn’t have the luck of them going in — and then look, it happened to me.”
Betis trail Atletico Madrid, fourth, by seven points having played one extra game.
However Diego Simeone’s side are focused on the Champions League and have played the reserves in many of their recent Liga games, giving the Andalusians a glimmer of hope of overhauling them to finish in the top four.