The visitors almost took the lead in the 12th minute as Francisco Portillo latched on to a pass deep inside the area before drilling a low shot towards the bottom corner, but the keeper got down well to make a good save.
The hosts had a chance to double their lead on the stroke of half time as Ruben Castro connected with a cross inside the area, but he couldn't steer his header on target.
Castro threatened again 10 minutes after the restart, beating the defence in the air once more before planting a header just wide of the post.
Malaga had a chance to equalise on the hour mark as Jesus Gamez hit a first-time shot from inside the area that flew narrowly past the upright.
Betis came close to all but sealing the points in the 66th minute when Leo Baptistao picked up the ball inside the area, but he couldn't keep his eventual shot down.
Juanmi was not to be denied next time, however, as he levelled things up for his side just six minutes from time with a close-range finish from Nordin Amrabat's through-ball.
The hosts almost regained the lead immediately afterwards when Alfred N'Diaye found himself in the opposition six-yard box, but Cabellero pulled off a fine save to keep the scores level.
The hosts could have rescued a point in second-half stoppage time when they were awarded a penalty, but Castro only served to compound their misery by hitting the crossbar from 12 yards to conclude a dramatic finale to the match.