"Make some noise for my baby father," the "Anaconda" singer told the crowd at Burgettstown.
Mill has been accompanying Minaj on her North American tour, opening as the support act for his girlfriend, reported E Online.
Just last week, a rumour had surfaced that 32-year-old Minaj had ended her relationship with 28 year old Meek - whose real name is Robert Rahmeek Williams - following his much-publicised feud with Drake via social media that erupted at the end of July.
Minaj has not officially made any statements but she did add fuel to the rumour by re-tweeting a fan's video of the shout-out later on Saturday evening, along with a number of emojis.