The 27 municipalities of the region of Southwest Finland (Finnish: Varsinais-Suomi; Swedish: Egentliga Finland) in Finland are divided into five sub-regions.

Åboland–Turunmaa sub-region

• Kimitoön (Kemiönsaari)
• Pargas (Parainen) (Väståboland/Länsi-Turunmaa between 2009-2011)

Loimaa sub-region

• Aura
• Koski Tl (Koskis)
• Loimaa (former arms: )
• Marttila (S:t Mårtens)
• Oripää
• Pöytyä

Salo sub-region

• Salo (former arms: )
• Somero

Turku sub-region

• Kaarina (S:t Karins) (former arms: )
• Lieto (Lundo)
• Masku (former arms: )
• Mynämäki (Virmo) (former arms: )
• Naantali (Nådendal)
• Nousiainen (Nousis)
• Paimio (Pemar)
• Raisio (Reso)
• Rusko (former arms: )
• Sauvo (Sagu)
• Turku (Åbo)

Vakka-Suomi sub-region

• Kustavi (Gustavs)
• Laitila (Letala)
• Pyhäranta
• Taivassalo (Tövsala)
• Uusikaupunki (Nystad)
• Vehmaa (Vemo)

Former municipalities

• Kuusisto (to Kaarina in 1946)
• Naantalin maalaiskunta (to Naantali in 1964)
• Angelniemi (to Halikko in 1967)
• Pargas landskommun (to Pargas in 1967)
• Uskela (to Salo in 1967)
• Maaria (to Turku in 1967)
• Kakskerta (to Turku in 1968)
• Hitis (to Dragsfjärd in 1969)
• Karuna (to Sauvo in 1969)
• Uudenkaupungin maalaiskunta (to Uusikaupunki in 1969)
• Paattinen (to Turku in 1973)
• Pyhämaa (to Uusikaupunki in 1974)
• Metsämaa (to Loimaan kunta in 1976)
• Karjala (to Mynämäki in 1977)
• Somerniemi (to Somero in 1977)
• Lokalahti (to Uusikaupunki in 1981)
• Kalanti (to Uusikaupunki in 1993)
• Loimaan kunta (to Loimaa in 2005)
• Karinainen (to Pöytyä in 2005)
• Mietoinen (to Mynämäki in 2007)
• Piikkiö (to Kaarina in 2009)
• Dragsfjärd (formed Kimitoön with Kimito and Västanfjärd in 2009)
• Kimito (formed Kimitoön with Dragsfjärd and Västanfjärd in 2009)
• Västanfjärd (formed Kimitoön with Dragsfjärd and Kimito in 2009)
• Alastaro (to Loimaa in 2009)
• Mellilä (to Loimaa in 2009)
• Houtskär (formed Väståboland in 2009)
• Iniö (formed Väståboland in 2009)
• Korpo (formed Väståboland in 2009)
• Nagu (formed Väståboland in 2009)
• Pargas (formed Väståboland in 2009)
• Askainen (to Masku in 2009)
• Lemu (to Masku in 2009)
• Merimasku (to Naantali in 2009)
• Rymättylä (to Naantali in 2009)
• Velkua (to Naantali in 2009)
• Yläne (to Pöytyä in 2009)
• Vahto (to Rusko in 2009)
• Halikko (to Salo in 2009)
• Kiikala (to Salo in 2009)
• Kisko (to Salo in 2009)
• Kuusjoki (to Salo in 2009)
• Muurla (to Salo in 2009)
• Perniö (to Salo in 2009)
• Pertteli (to Salo in 2009)
• Suomusjärvi (to Salo in 2009)
• Särkisalo (to Salo in 2009)
• Tarvasjoki (to Lieto in 2015)