He also shared footage of the moment he and Rachel brought their little girl home, as well as snaps from the hospital and of their little family of three.
"@rachevans_ we're in for one hell of a ride and I'm so grateful to be sharing it with you. You are amazing!" he said in honour of his partner.
"Thank you to everyone who has helped out over the last few days. Especially @mack_the_berner for hanging out with our man Bowser for the weekend."
Rachel also shared photos from the moment they first brought daughter Gigi home, captioning the snaps: "Our little family are home ... meet Gigi Bloom Mann."
She and Pete reconnected after dating "casually" before his stint on The Bachelorette, where he was chosen as Becky Miles' winner in the finale.
Despite winning Becky over, Pete and the reality star called it quits just days after filming wrapped and he practically disappeared from the spotlight.
"We spent about three days together and we had a lovely time" Becky told Now To Love after her finale with Pete aired.
"I think that's why I was quite blindsided when he broke it off because, you know, in those moments he was saying all the right things."
Behind the scenes, he was reconnecting with Rachel, telling the Daily Mail in late 2020: "I simply fell head over heels.
"We've now met each other's families and will be spending Christmas together, including a secret little getaway."
Now the beautiful couple are ready to take on the new roles of mum and dad to baby Gigi, something their beloved dog Bowser may take some time to get used to.
And don't worry, Becky found new love of her own: she's now dating James Bevin and the couple are expecting their first child later this year.
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This article first appeared on our sister site, Now to Love.