Wearing a green blazer and purple shirt, the 71-year-old musician smiled widely as he followed his ex outside, who looked even happier in a white shirt and sunglasses, reported Daily Mirror.
Hall split from Jagger 15 years ago but remains close for their four children.
Jagger was recently spotted kissing a woman on his hotel balcony. The woman was later identified as ballet dancer Melanie Hamrick, whom the singer met backstage at a Rolling Stones gig days before his girlfriend L'Wren Scott, 49, was found dead in her New York apartment.