John Kerr, 51, registered as a county co-ordinator with the charity in 2011 to help raise funds for ex-servicemen and women.
He had an agreement with a pub that he would exchange donated coins for notes, because it made it easier for him to bank.
The court heard Kerr took charity buckets to the Quarter Gill pub on Glasgow's Dumbarton Road to exchange the money for notes.
But suspicions were aroused when Kerr was suspected of living beyond his means.
Some of the notes given to him by pub staff to be banked were marked and seen coming back over the bar.
The charity and police were later contacted.
When Kerr was questioned he claimed he had no money from the charity at his house.
But the day after being interviewed he took more than £5000 to the bank and told Help for Heroes it was a year's worth of Asda donations.
After a trial at Glasgow Sheriff Court, Kerr, of Scotstoun, Glasgow, was convicted of embezzling £6910 between February and December 2012.
He will be be back in court to be sentenced next month.