Preliminary results showed Mr Cadogan won with a clear majority of 4274 votes over his deputy mayor and challenger Hamish Anderson's 1463.
Only two of Clutha's wards and one community board held elections - Lawrence-Tuapeka (also its community board) and Balclutha.
Councillor Geoff Blackmore retained his position receiving 310 votes while challenger Paul Tansley received 150.
Ron Davis (1742) , Ken Payne (1465), and Hamish Anderson (1177) return as Balclutha councillors joined by newcomer Jo-anne Thomson (1117). Grant Driver (1069) and Stewart McDonell (792) were unsuccessful.
Geoff Davidson, Rowena Paterson, and Garry McCorkindale return to the Lawrence-Tuapeka Community Board, joined by newcomers Brent Taylor, Malcolm MacLeod, and Liz Forbes.
Rochelle Langley failed to return to the board, and Paul Tansley was also unsuccessful.
The voter return was 49.16%, being 5796 voting papers.
Meanwhile in Gore, incumbent mayor Tracy Hicks was elected unopposed.
