Ards suffered relegation and will be replaced by Institute in the Premiership as the Londonderry club won the Championship title.
The North Down club needed Bangor to win the Championship which would have handed Ards a play-off against Institute, who beat Limavady 2-0.
Ironically, Ards-bound Josh Cahoon's goal earned H&W Welders a 1-1 draw against Bangor at Clandeboye Park.
Cahoon has agreed a pre-contract deal to move to Ards in the summer.
However, his Welders goal ultimately condemned his soon-to-be club to the drop.
Ards went into the final Premiership game against Ballymena United completely at the mercy of events at Clandeboye Park and Drumahoe.
The Ballymena game finished 1-1 with William Faulkner levelling for Ards after James McCabe had put the Braidmen ahead.
Things appeared to be going Ards's way when Jordan Forsythe put Bangor ahead against the Welders a minute before half-time at Clandeboye Park.
That left Bangor on course to win the Championship title even though the Seasiders have already made clear that they would not be accepting a place in the Premiership next season.
However, Cahoon's 67th-minute equaliser totally changed the scenario as it left Institute at the top of the Championship table.
Stephen O'Donnell put Institute ahead on 30 minutes after he had been only introduced as a substituted moments earlier.
Michael McCrudden notched Institute's second goal three minutes before half-time.