Fonua is a surname. Notable people with the surname include:
Amini Fonua (born 1989), Tongan swimmer Mahe Fonua (born 1992), Australian rugby league player Opeti Fonua (born 1986), Tongan rugby union player Semisi Fonua (1911–1968), Tongan noble and politician
See also Addin Fonua-Blake (born 1995), Australian rugby league player Penisimani Angelo Fonua Siolaa (born 1994), Tongan male weightlifter