The 11-strong group, run by husband and wife team Alex and Saiphin Moore, will launch a 60-cover restaurant with a theatre kitchen and 25-cover private dining room on the former Belpassi Bros site on Tooting High Street on 22 March.
A further site on Ealing Broadway is also planned for early summer.
Rosa’s ran its first vegetarian-only pop-up at its Dean Street this year, though the new openings will serve its original menu with meat dishes.
“Both areas have a loyal and growing local foodie community, so offer the ideal locations for the new sites,” says Gavin Adair, managing director at Rosa’s Thai Café.
The group opened its first site in London’s Spitalfields in 2008 and has since expanded to 11 restaurants in the capital.
Rosa’s is also expected to open its first regional site in Liverpool’s Albert Dock area this year.
It was rumoured to be opening in Oxford’s Westgate shopping centre but is understood to have turned down the site.