Kemp had too much speed on the 21km run for Docherty, pulling away to win in 3:56:02, 34 seconds ahead of the Kiwi, the two-time Olympic triathlon medallist making a full-time move into longer-course racing this year.
Ellice, who races on the ITU Olympic distance circuit, finished an excellent third in 3:58:23.
The inaugural race also saw an Australian take out the women's title - Annabel Luxford leading from start to finish to come home in 4:19:18, almost six minutes ahead of Caroline Steffen of Switzerland, with American Meredith Kessler third.
Anna Ross was the best of the New Zealand women, finishing fifth.
The race was held in drizzly, humid conditions, and saw competitors start with a 1.9km swim in the Viaduct Harbour and cycle the 90km bike leg over the Harbour Bridge and around part of the North Shore. The run was a two-lap affair from the Viaduct along Tamaki Drive and back.
Ironman 70.3 Auckland results:
Men: Christian Kemp (Australia) 3:56:02, 1; Bevan Docherty (New Zealand) 3:56:36, 2; Clark Ellice (New Zealand) 3:58:23, 3; Paul Ambrose (UK) 3:59:26, 4; James Hodge (Australia) 4:00:55, 5.
Women: Annabel Luxford (Australia) 4:19:18, 1; Caroline Steffen (Switzerland) 4:25:15, 2; Meredith Kessler (USA) 4:29:24, 3; Sarah Crowley (Australia) 4:32:04, 4; Anna Ross (New Zealand) 4:34:25, 5.
