In December 1846, Brunner commenced an expedition, accompanied by four Māori including Kehu, which began from Nelson. The party travelled down the Buller River and along the West Coast reaching as far south as Tititira Head, near Lake Paringa before returning to Nelson via the Arahura River. This arduous journey, which at one stage saw one of his legs paralysed, took him 550 days. He received honours from the Royal Geographical Society and the Société de Géographie (French Geographic Society). He continued to work as a surveyor and in 1851 was appointed Government Surveyor. He surveyed the sites, which he and Heaphy had scouted on previous explorations, for what would become the towns of Westport and Greymouth. He retired in 1869 and died of a stroke on 22 April 1874.