A four-gettable start to the season for United at Linfield
Aaron Burns scored twice in the opening half to lay the foundations to this win at Windsor Park.
Andy Waterworth added a third with a close-range finish in the 85th minute, with Reece Glendinning slotting home the fourth in the final minute.
Ballymena had defender Jim Ervin sent off for a last-ditch tackle on Guy Bates in the 77th minute, compounding a miserable day for the Sky Blues in south Belfast.
Waterworth showed his pace in the 15th minute but could only trickle his shot wide of the post under pressure from Johnny Taylor.
At the other end an intricate free-kick involving Nathan Hanley and Neal Gawley eventually led to a low pass to Tony Kane whose first-time shot was always rising over the bar.
The opening goal arrived in the 35th minute with a bullet header from Burns.
Kirk Millar was the provider, curling in a pin-point corner for Burns to thunder home from five yards.
Ballymena tried to respond but Gawley’s header was easily gathered by Ross Glendinning.
Burns claimed his and Linfield’s second goal in the 41st minute.
Stephen Lowry was industrious down the left before poking the ball into the path of the onrushing winger who rifled his shot high into the net.
Cushley tried an acrobatic overhead kick in the 46th minute but the effort sailed wide.
Glendinning was forced into a diving save from Cushley’s low drive from 30 yards in the 52nd minute.
Waterworth had the ball in the back of the net in the 68th minute, but the scrambled effort was ruled out for offside.
Ervin was shown a straight red card in the 77th minute when he clipped the heels of Bates on the edge of the area – referee Andrew Davey deeming Ervin to have been the last defender.
From the resulting free-kick Blayney denied Niall Quinn with a superb save, and then the Ballymena goalkeeper saved from Matthew Clarke.
The third goal arrived in the 85th minute, Waterworth finishing off from close range after Ballymena failed to deal with Quinn’s corner.
And Glendinning bagged the fourth in the final minute, the defender finishing off after Waterworth’s effort had rebounded off the post.
Ballymena boss Glenn Ferguson was left to rue a number of defensive errors on Saturday.
“We knew it would be tough, but we made mistakes,” he said.
“We worked tirelessly on defending set pieces, but we ended up conceding three goals from set pieces.
“I think we frustrated Linfield for 35 minutes but we then shot ourselves in the foot.”
Ro. Glendinning, Haughey, Waterworth, Lowry, Bates (Salley 86), Millar (Murray 86), Burns (Quinn 71), Ward, Clarke, Mulgrew, Re. Glendinning.
Subs not used: Deane, Hegarty.
Blayney, Ervin, Taylor (Taggart 46), McVey, McBride, Gawley (Henderson 54), Thompson (Jenkins 59), T. Kane, Hanley, Tipton, Cushley.
Subs not used: E. Kane, Ruddy.
Referee: Andrew Davey