The bakery, which sells breads and pastries as well as cakes and sandwiches, has taken on a site in Highgate, which is due to open in the spring.
Sourdough Sophia was founded by baker Sophia Handschuh and her husband Jesse Sutton-Jones in their flat during lockdown and became an overnight success.
Following a successful crowdfund that attracted and nearly 600 backers, the pair opened their first bakery in 2020 in Crouch End.
A second bakery opened last year on Essex Road in Islington.
Announcing the new site on Instagram, Handschuh says: “One of the reasons I’ve been so quiet is because I’ve been working really hard on getting this deal over the line, and I’m glad to say we’re finally getting there.
“I’m not gonna lie, the market has been tough recently and it’s been really hard to find affordably good sites, in good condition, in great neighbourhoods which is why this has taken many more months than I wanted!
“Rather than opening up here there any everywhere, Jesse and I always want to open sites in places that we that we know and that has a community that really resonates with us and our culture.”
Highgate was previously home to Handschuh and Sutton-Jones before they moved to Crouch End, with Handschuh describing the location as ‘pretty special.
“We spent many a weekend strolling around here and enjoying the local park and beautiful views of London in our early 20s.”