[1] In 1966 he completed a PhD from Victoria University of Wellington, with a thesis was on "Educational reorganization for national development in Tonga".
In early 1968 he was appointed acting Minister of Finance while Mahe 'Uli'uli Tupouniua was seeking medical treatment in New Zealand.
[8] Following the 2005 Tongan public service strike he was appointed to the National Committee for Political Reform which recommended a transition to democracy.
Sempisi Langi Kavaliku was bestowed the Royal Chiefly title of Hu'akavameiliku by His Late Majesty King Tupou IV as the title was to be bestowed on his father Sione Ma'afu but refused it as he was already The Honourable Kavaliku, so the title was bestowed upon his heir thus Dr Sempisi Langi Kavaliku was styled The Honourable Hu'akavameiliku of Ha'asini.
Hu'akavameiliku married Lady Fuiva Kavaliku and had many children in their care.