The Oscar-winning actor reached the milestone in August 2010 while he was filming This Must Be The Place, alongside Bono's daughter Eve Hewson, in the Irish capital.
He left his birthday celebrations in the hands of the U2 rocker, who organised a bash with guests including the actor's children and country legend Kris Kristofferson - and Penn was delighted with the party.
The star tells Britain's Telegraph magazine, "He (Bono) takes us to lunch, then on a literary walking tour, then up the stairs of some famous pub - and there waiting are (folk band) the Dubliners. They play for five hours, my son sits in on guitar, we drink Guinness...
"And he didn't just sing me Happy Birthday. He sang me (Me and) Bobby McGee (by Kristofferson)."