Gamage is a Sinhalese or Welsh surname. Notable people with the surname include:
Anoma Gamage, Sri Lankan politician
Barbara Sidney, Countess of Leicester (1563–1621), Welsh heiress
Chamila Gamage (born 1979), Sri Lankan cricketer
Dharshana Gamage (born 1979), Sri Lankan cricketer
Harry Gamage (1900–1994), American football coach
Janak Gamage (born 1964), Sri Lankan cricketer
K. A. Gamage (died 2009), Sri Lankan army officer
Lal Dharmapriya Gamage, Sri Lankan architect and politician
Lalith Gamage, Sri Lankan academic
Piyasena Gamage (born 1949), Sri Lankan politician
Saheli Rochana Gamage (born 1988), Sri Lankan singer