The reality TV star, who won the show in 2018 with his former partner Dani Dyer , revealed on social media that he had welcomed a daughter on Friday.
The 28-year-old did not reveal the identity of the baby's mother. However, he said that they are not in a relationship.
In an Instagram post, in which he was seen cradling the newborn called Blossom, Fincham said that he normally shares most of his life on social media but decided to keep this "blessing" private until now.
“I’m just a normal geeza, who went on a tv show, which throws you straight into the public eye… which I will forever be grateful for," he said
“However I knew for myself I needed personal time and to keep this part of my life private to prepare for this new responsibility and part of me that will change my life forever.”
Fincham said that having a baby is “undoubtedly the best thing that has ever happened to me and it’s true what they say, the instant feeling of love and connection you have with your child is a feeling like no other”.
He continued: “I want to thank my family and friends for your continued support, also to my little girls mother, who has been totally AMAZING throughout.
“Although we are not together we are great friends as we have been for many years and our priority is co-parenting our beautiful baby girl. Both mum and baby are doing great.
“I am now a proud dad to a healthy baby girl Blossom Fincham born 8lb 2oz on 24th January 2020.”
Fincham and Dyer, the daughter of EastEnders actor Danny Dyer, won the £50,000 prize when coming first in Love Island in summer 2018.
They remained in a relationship for around eight months after the series ended, calling things off 10 months ago in April last year.
Shortly after their split, Fincham took part in E4 series Celebs Go Dating.
Celebrities and other Love Island stars congratulated Fincham after his announcement, with his former co-star Eyal Booker expressing his shock, writing: “Whaaattt!!! Congratulations bro! Wishing you health & happiness. You’re going to be the best dad.”
Dr Alex George, who also took part in Love Island 2018, wrote: “I’m so chuffed for you. Anything you, mum or the baby need mate just let me know.”