Dad-to-be Conor shared his own post of himself, Mary and Mary's seven-year-old daughter Chanel dressed in pink and white, posing in front of a flower wall.
"A great day with beautiful people. Can’t wait to meet this little lady," he penned in his caption.
As for the guest list, it was a who's who of Bachelor alumni including several of Mary and Conor's Paradise co-stars such as Niranga Amarasinghe, Jessica Brody and Janey Birks.
Niranga, who formed a close bond with Mary on the reality show, posted a photo of himself holding Chanel posing with Conor and Mary as well as one of himself and Mary, remarking on the couple's sweet reality TV love story.
"If I never get my happily ever after at least I can rest easy knowing I was a part of making the most beautiful love story that has ever come out of reality tv," he captioned the post.
"Two of the most kindhearted people deserve this incredible life together. I am craving this love story so fingers crossed for me. Hopefully sooner rather than later."
Needless to say fans shared their support with the reality TV fan favourite, who first starred on Angie Kent's season of The Bachelorette.
"Fingers crossed for you," one wrote.
"Hopefully you are the next bachelor!" exclaimed another.
Bachelor in Paradise star Jessica Brody also shared some cute photos from the baby shower, including a photo of herself, Mary, Niranga, Janey and season seven Bachelor contestant Nikki Ferris.
"Love isn’t dead," Jess noted in her caption.
The tattooed beauty, who briefly dated Paradise bad boy Ciarran Stott, also penned a heartfelt tribute to Mary alongside a photo of the two of them.
"My awkwardness definitely shows in group photos but I adore this woman so much. She yells at boys that hurt my feelings @maryviturino18 can’t wait to meet baby Canning."
In October last year, Mary and Conor revealed their exciting baby news with fans.
"We can’t wait for the newest member of our little family. @maryviturino18 and I are over the moon and Chanel is very excited to be a big sister," dad-to-be Conor wrote in his Instagram announcement at the time.
"I know I haven’t been active lately, so I’m happy to finally be able to share the news that @conorjcanning and I are having a baby next year," Mary wrote in her own post.
The first Bachelor in Paradise baby is due in early May 2021.