The actor – who we fell in love with as Zack Morris – welcomed a baby boy called Dekker Edward Gosselaar on 30 September with his wife Catriona McGinn.
He told People that the couple are "overjoyed" and "madly in love" with their new arrival, adding: "He is healthy and just perfect – all we could ask for."
Mark-Paul, who currently stars in comedy-drama Franklin & Bash , is also father to daughter Ava, seven, and nine-year-old Michael from a previous marriage.
The 39-year-old tied the knot with advertising executive Catriona in July 2012 and they announced earlier this year that their first child was on the way.
Mark-Paul isn't the only Saved By The Bell alum to welcome a baby in September: his co-star Mario Lopez (AC Slater) became a second-time dad last month when wife Courtney gave birth to their son Dominic. He's also dad to daughter Gia, three.
Other SBTB stars with babies include Tiffani Thiessen (Kelly Kapowski), who is mum to daughter Harper, three, and Elizabeth Berkley (Jessie Spano), who is mother to one-year-old son Sky.
More celebrities who became parents in 2013 below!
Copyright: Love & Lust London