Mr Key said he was thankful to be invited to the Father's Day service. He recounted his own family's story, including being a young boy when his father died from a heart attack.
Mr Key said his mother's example in the years ahead taught him the value of hard-work and honesty.
"In my case I didn't know my father, I had one memory of him, he didn't play a particularly important role in my life...but my mother was actually able to fill that role, the role of my father and my mother."
Mr Key's visit less than two weeks out from election day is a high-profile push to weaken Labour's traditional popularity with Pasifika voters, but he insisted he was not attending church to ask for votes.
"Today is a Father's Day celebration, it's a Sunday, it's not a day for politics and all that sort of stuff, so we'll leave it at that."
Labour Party leader David Cunliffe spoke at the same Malaeola Community Centre last month.
Mr Cunliffe spoke after the monthly Mass, which is the normal time for notices and announcements.
At the time, diocese spokeswoman Lyndsay Freer said there was no question of partisanship, citing Mr Key's impending visit.
