Eighteen-year-old sensation Oliver Torres got the hosts off the perfect start on his full league debut with the fastest goal this season after just 13 seconds.
Villa then made the game safe with a quickfire brace just after half-time.
La Liga's top-scorer Diego Costa took his tally to 13 goals in 13 games in all competitions when he slotted home from Villa's pass 25 minutes from time before Gabi rounded off the scoring in stoppage time.
Torres had been handed a start in place of the injured Arda Turan and the Spanish Under-21 international was in the right place at the right time as he slotted home at the back post from Koke's cut-back.
Diego Godin should have made it two on 16 minutes when he was left in space inside the box but somehow headed Torres' perfect cross wide.
Costa also ought to have scored twice before half-time as he firstly slotted wide when clean through on goal and was then denied by Betis keeper Guillermo Sara who stood up well to turn his effort behind for a corner.
Sara had to be replaced by Stephan Andersen at half-time due to an injury, but the Dane's first job was to pick the ball out of the net as Villa neatly flicked home Costa's cross at the near post eight minutes after the restart.
And three minutes later Villa smashed home his fifth goal of the season after Koke's pass towards Torres deflected fortunately into his path.
Costa finally got the goal he craved when Villa's lovely through ball allowed him to plant a left-footed finish into the far corner.
He was then withdrawn with one eye on the upcoming league matches against Granada and Athletic Bilbao in mind, but Atlético still had one more goal in them when Gabi fired low into the corner with the last kick of the game.
Villarreal strengthened their hold on fourth spot with a 4-1 thrashing of Valencia at the Madrigal.
Early goals from Ikechukwu Uche and Hernan Perez put the hosts 2-0 up at half-time before a Giovanni Dos Santos double completed the rout after the break.
Real Sociedad continued their recovery with a 3-0 win over the still winless Almeria to move up to ninth.
Sevilla also moved into the top half of the table with a 2-1 win over 10-man Osasuna.