Seen near the couple's family home in London, the little one — whose named has not been been shared publicly — was kept close to his father’s chest in a hands-free baby carrier and covered up in a white hat.
The 34-year-old actor, for his part, looked dashing in a dark peacoat, turtleneck sweater, cropped trousers and cool Chelsea boots.
Also in tow for the afternoon stroll was the family dog, who donned his own stylish yellow raincoat.
Harington and Leslie didn’t make an official announcement of the arrival of their first child together. Instead, the news was confirmed when the family of three was spotted out London together on Tuesday, February 16.
The couple first announced they were expecting their first child back in September. The exciting news was revealed when the 34-year-old mom-to-be debuted her growing baby bump on the cover of the U.K. digital magazine Make.
A month later, Leslie addressed her pregnancy again. "I am thrilled to be expecting," she told The New York Post, "and I can't wait to meet the new member of our family!"
The English actress starred as Ygritte opposite Harington’s Jon Snow on Game of Thrones from 2012-2014. They made their red carpet debut in 2016 at the Olivier Awards in London and confirmed their engagement in a newspaper announcement in 2017.