Atletico got on the board with goals from Yannick Carrasco and Joao Felix, and an own-goal by Betis defender German Pezzella, under heavy rain at the Wanda Metropolitano Stadium.
It was its first win after three matches consecutive draws against Levante and Real Sociedad in the league and a loss to Liverpool in the Champions League.
The victory moved Atletico within two points of leaders Real Madrid, Sevilla and Real Sociedad. Madrid and Sevilla won their matches on Saturday, while Sociedad hosts Athletic Bilbao in the Basque Country derby later Sunday.
Atletico’s usually solid defense had faltered recently, having conceded seven goals in its last three matches. Diego Simeone’s team next visits Liverpool in the group stage of the Champions League.
“It was very important not to concede any goals to boost our confidence on defense going into the match against Liverpool,” Carrasco said.
Betis, which had won five of its last six league matches, stayed a point behind Atletico and has played an extra game. Manuel Pellegrini’s side had won two in a row in all competitions.
Carrasco opened the scoring with a shot from inside the area in the 26th minute. The hosts added to the lead after Pezzella headed a cross from a corner into his own net in the 63rd, and Felix sealed the victory after a long run in a breakaway in the 80th for his first goal of the season.
Felix’s goal was initially disallowed for offside but video review confirmed that the Portugal forward was onside at the time of Carrasco’s pass.
Atletico also had a goal by Mario Hermoso disallowed for offside early in the second half.
Simeone watched the match from the VIP tribunes after being sent off in the team’s 2-2 draw at Levante in the previous round.