The "7 Rings" singer hit the stage at the PPG Paints Arena in Pittsburgh, Pennsylvania for the latest stop on her Sweetener World Tour, and according to Us Magazine the star was visibly overcome with emotion throughout the performance.
During her opening number Raindrops (An Angel Cried) - which is widely rumoured to be about the breakdown of the pair's relationship - she was unable to finish the song as she began to cry. She also choked up towards the end of the show when she attempted to sing Mac's name during "Thank U, Next", before fans completed the lyrics for her as she regained her composure.
Before the show began, it was clear the evening would be in honour of the late rapper, real name Malcolm McCormick, as several of his biggest hits played over the speakers in the venue as fans took to their seats.
The concert also coincided with the release of singer/ rapper Anderson .Paak's band the Free Nationals' new single Time, which features a guest appearance from Miller and is his first posthumous release.
Ariana and Mac dated from summer 2016 until spring 2018. The musician died at the age of 26 in September from an accidental overdose.