Other Kiwi personalities, including The Hits breakfast hosts and mothers Toni Street and Laura McGoldrick, commented on the post.
"What a sweet photo of you guys," Street wrote.
"Beautiful photo! Happy birthday little one," McGoldrick added.
According to mum Gemma, Richie is baby Charlotte's favourite parent.
In a pre-birthday celebration Instagram post, she wrote: "Is there anything cuter than a Dad swimming with his baby?"
"These two have spent some quality time together this week while I've been training and secretly I think he's the favourite #daddysgirl."
Gemma McCaw was recently named in the Black Sticks' squad as the team builds towards the 2020 Olympics, returning to the fold after having played 246 matches before retiring in October 2017.
As a result of her increasing workload, she told Now To Love that her husband and her mother Michelle would both be stepping up to help out as she ramps up her training in an effort to make the Games.
Her mother would take a year off from teaching to help with Charlotte, while Richie McCaw, who now works as a helicopter pilot, will also scale down "so they'll share the care of Lottie when I'm training".
Last month Gemma McCaw opened up about the "challenges" of juggling motherhood and her return to the Black Sticks in an interview with Radio Sport's D'Arcy Waldegrave.
"A little tiny part of me felt that there was a little bit of unfinished business.
"I felt like I really missed getting out there with the girls and playing the sport that I always loved. I filled in for a club hockey game when Charlotte was 4 months old and I kind of crossed the line out onto the field and I had that white line fever again.
"That's where it all started. I was fortunate enough to play NHL and then some time in the Aussie league and that's when I guess I started to get a little bit more serious about it and think 'I would actually love to play again at that high level'.
"A year ago just before having Charlotte I didn't think I'd probably be lining up back in the team. But [I'm] grateful for the opportunity and very excited with the year ahead and what's to come."
