The Championship side won 5-0 with Chris Dawson bagging a hat-trick and further goals from Eoghan Stokes and Matt Smith.
However, the result was never a focal point of the glamour friendly, with over 3,000 fans making it a sell-out at Mourneview Park.
Healy, who played for Leeds United for three seasons from 2004 to 2007, came off the bench on 23 minutes and received a rousing reception from both sets of fans.
The 34-year-old showed he still posed a goal threat and almost capped a great night for the Lurgan Blues with a goal.
However, the Northern Ireland international record goal scorer said his appearance in a Glenavon shirt was a one-off.
He said: "I enjoyed the game, but it was a one-off.
"I was only too pleased to help Glenavon and Gary Hamilton out for their anniversary game.
"Gary has done a fantastic job and it was great to see a packed house for this very special game. It was nice for me too that it was against my former club where I really enjoyed my time at Elland Road."
After Dawson gave Leeds the lead Glenavon were unfortunate not to draw level before the break with Guy Bates, David Rainey and Healy all going close with efforts on goal.
Leeds stepped up a gear in the second half with Dawson grabbing two more, one from the penalty spot, before Stokes and Smith made it a pleasing result for their fans and coach Neal Redfearn.
Glenavon continue their pre-season games this weekend with two matches in Dublin, they play Swords Celtic on Friday night followed by Skerries Town on Saturday.