Cosmin Olaroiu's men only needed a point against Al Wasl to be crowned champions, but came from behind to record their eighth league victory in succession.
Ricardo Oliveira opened the scoring inside six minutes, before Al Ahli responded in the second half with goals from Ahmed Khalil and Grafite.
Al Ahli, who are also through to two domestic cup finals and well placed to qualify for the next stage of the AFC Champions League, have now claimed six league titles and will be hopeful of enjoying further success before the season comes to an end.
Al Shabab have fallen away badly in recent weeks and now sit 15 points behind the champions after their third straight loss, a 2-1 defeat at the hands of resurgent Al Nasr.
Sixth-placed Al Nasr, by contrast, are unbeaten in seven league games, having secured victory on home soil through Ibrahima Toure's 79th-minute winner.
Match-winner Toure was sent off together with Al Shabab's Azizbek Haydarov with seven minutes remaining.
Bottom club Al Shaab's relegation was confirmed with a humiliating 5-0 reverse at home to Al Ain.
The prolific Asamoah Gyan scored a hat-trick, moving to 24 goals for the season in the process, as Al Ain ran riot.
Dubai appear certain to follow Al Shaab out of the top flight. They were thumped 5-1 at home by Al Dhafra and are now seven points from safety after Emirates beat Al Jazira 3-2.
Elsewhere, Sebastian Tagliabue scored all of Al Wahda's goals in a 4-1 triumph over Ajman and third-placed Al Sharjah ran out 3-1 winners at Bani Yas.
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