The family purchased the listed property next to their St Petroc's bistro earlier in the decade and started refurbishing the building in 2015.
Ruby's serves a selection of boutique gins as well as Rick and Jill's favourite cocktails, beers, wines and nibbles.
It is the family's tenth venue to open in Padstow and 17th in the UK overall.
Jill Stein said: “The project has been a labour of love. The concept for the bar was easy really, I wanted to develop it as the sort of bar that you would expect to find in Padstow at the turn of the century, but sexy!”
Jill and Rick’s eldest son Edward has managed the development of the site, with Jill and daughter-in-law Kate Stein overseeing the interiors.
The bar's design feature an oak staircase crafted by a local carpenter, a slate floor and Falmouth granite basins.
“We have collected lots of old marine art for the walls and decorative items from the local antique shops in Wadebridge,” said Jill.
“It has been a great project to work on and I think it looks pretty amazing, a lot of thought has gone into it, a huge amount of blood, sweat and tears.”
Rick Stein first opened The Seafood Restaurant in Padstow in 1974, and now runs restaurants across Cornwall, Dorset and Winchester.
He will open his 18th venue in Marlborough later this year.
The chef pulled out of a planned opening in Eastbourne in July blaming concerns over the EU referendum result, according to The Eastbourne Herald.
Ruby’s bar opens daily from 12 noon – 11pm.