The Hearts center back was called into action as early as the eighth minute taking over from the stricken Nuhu Musah and he showed nerves of steel to shoot past Jobe Modou in the 99th minute to earn Maxwell Konadu's side qualification into the group stage.
Hearts captain Thomas Abbey and striker Kwame Kizito were handed starts but the latter gave way for Stephen Sarfo late in the game.
Patrick Razak was introduced in the second half to help breakdown the stubborn Gambia defense but the most telling contribution as the goal came from the boot of Abbey, whose snapshot in the box was adjudged to have come off the hand of a Gambia defender.
Atingah calmly skirted past The Gambia keeper to send the home fans into absolute delirium.
Winful Cobbinah was an unused substitute on the day.
[Picture credit: Backpagepix/ Muzi Ntombela.]