He also prayed before the tomb of controversial Bishop Samuel Ruiz.
Hundreds of faithful are in the Manuel Reyna Stadium to meet him.
Morelia gets ready for the Pope
A million and a half people are expected to bear witness to his visit.
A little girl in a wheelchair presented Francis with a handmade Valentine's Day card.
The Mass is to take place in an outdoor field with an estimated capacity of 400,000.
He drove from the airport to the capital's south side in an open-air popemobile waving to the crowds lining the route.
Here are five things to know about Francis' trip to the largest Spanish-speaking Catholic country in the world.
The pope will visit Mexico City, celebrate Mass with indigenous communities in Chiapas, speak with young people in Morelia, the capital of violence-torn Michoacán state, and visit prison inmates in Ciudad Juárez.
"El Chapo" took a photo with the comedian, as he did with actor and producer Sean Penn.
Hayek will visit Mexico in January to promote the animated film based on the book of 26 prose poetry essays written in English by Lebanese Kahlil Gibran.