Knowing a victory would secure a top-five place, the hosts made the best possible start by opening the scoring after just nine minutes when Cucho Hernández wonderfully found the bottom corner from outside the area.
Antony then wasted a chance to double the advantage, whereas Eder Sarabia’s men, who started the night just outside the relegation zone, struggled to make any impression on the game.
Their equaliser, four minutes before the break, therefore came out of nowhere. Hector Fort, on loan from Barcelona, was the man who got it, clinically finding the far top corner from inside the area with just his second league goal of the campaign.
That gave the visitors the momentum, but Andre Silva and Aleix Febas wasted two huge openings, while Grady Diangana controversially had a goal ruled out for a handball in the build-up on the stroke of half-time.
Any hopes the visitors harboured of finding a second were all but extinguished when Leo Petrot was sent off shortly after the restart, with the defender dismissed for a dangerous, high tackle where he raked his studs down the trailing leg of Antony.
That opened the door for Manuel Pellegrini’s side to retake the lead, and Hernandez duly saw a header deflected onto the bar, before Giovani Lo Celso had a strike easily saved.
Betis had lost just one of the last nine home head-to-heads, and they had half an hour to find a winner.
They needed just eight of them, though, as Pablo Fornals broke a two-month drought with a screamer from distance that arrowed into the top corner.
The floodgates threatened to open from then on, with Abde Ezzalzouli denied by goalkeeper Matías Dituro after rapid counter attack, and, after Álvaro Rodríguez had blazed over at the other end, Isco missed the target from just inside the box.
Elche threw on a string of attacking substitutes as they looked to avoid a third game without defeat, but wayward finishing proved to be their downfall.
Such is the incredible relegation picture in La Liga, they could be in the relegation zone by the next time they play, against Getafe on Sunday, whereas Real Betis - who could have added a third through Hernández in injury time - extended their unbeaten run to seven fixtures.
Flashscore Man of the Match: Diego Llorente (Real Betis)