The Formula One champion spent the day hanging out with Nicole's three nieces, and took to Instagram to share a photo of his little "monsters".
"My favourite lil ones. Been so much fun spending time with you!" wrote Lewis, tagging Nicole's younger sister Keala in the caption.
Lewis Hamilton spent the day with Nicole Scherzinger's nieces
The photo showed the close bond that Lewis still shares with Nicole's family. Fans were quick to comment on their hope for a reconciliation, with one writing: "Lovely, hope u miss Nicole get her back & marry her Champ."
"Still hoping for you and @nicolescherzy. This pic speaks a lot about your connection with her and her fam," wrote another.
Nicole, 38, and Lewis, 31, dated on-off for eight years. They split in February 2015.
Nicole with her sister Keala's daughters
Five months after their break-up, Nicole started dating tennis star Grigor Dimitrov. Over the summer she told Fabulous magazine: "We've been together for quite some time now, so I'm just living in the moment and I'm happy.
"It's good for girls to be with nice guys. Respect the nice ones – they can win! He's so damn cute."
Speaking about her ex Lewis, she added: "I think that we... wish each other well. In all honesty, it's in my past and I'm all about keeping the past in the past."
The family pictured in New York
Lewis, meanwhile, has been linked to Rihanna and models Winnie Harlow and Barabara Palvin, although he admitted that he has been focusing on his career.
Speaking during an interview on The Jonathan Ross Show last year, Lewis said: "I've been in two relationships in my life, I was 18 to 22 and 23 to 30 and so I missed the single life that all my friends had and now I've just been throwing myself at work, I've worked harder than ever this year, as I said I've travelled like crazy, I've experienced everything I want to experience."
He also admitted that he had been dating occasionally following the break-up. "Occasionally yes," Lewis smiled. "I'm enjoying it, it's really good fun, it's a fun period of time in my life."