John Howell was baptised at Eastbourne, Sussex, England, probably on 8 July 1810, the son of William Howell and his wife, Mary Collings. At the age of about 12 he stowed away on a smuggling vessel; apprehended on the vessel's return from France, he was released when found to have no connection with the smugglers. He promptly stowed away on a ship bound for Australia, became first mate on a whaling ship, and arrived at Kāpiti Island, New Zealand, in 1827 or 1828. Here he engaged in whaling and the export of greenstone to Australia.
He had made the acquaintance of the whaler and trader Johnny Jones in Australia, and after serving at his station at Waikouaiti was sent with three ships to establish a station in Foveaux Strait. According to oral tradition Howell set up his station at Jacobs River (Aparima River) in 1834, although other sources suggest it may have been in 1836 or 1837, with his flagship Eliza and crews of nearly 60 Europeans and some 200 Māori. Howell established friendly relations with local Ngāti Māmoe, but his refusal to take a Māori wife was regarded as an insult by the Māori. After an altercation he married Kohikohi, daughter of Horomona Patu, of Centre Island; she brought him a dowry of a large area of land between the Waimatuku Stream and Jacobs River. Kohikohi died about 1841, leaving two young children, and in 1845 Howell took a part-Māori wife, Caroline Brown, also known as Koronaki. The marriage was solemnised on 17 September 1846 at Waikouaiti; they were to have 17 children.
As manager and later owner of the whaling station Howell stamped his authority on the settlement. He held regular Sunday church services, frequently followed by country dancing to the accompaniment of his violin. He encouraged the station's men to establish farms in the area, bringing cargoes of tools and equipment from Australia, planting fruit trees and establishing vegetable gardens and household livestock. In 1843 he was joined by his half-sisters Ann Paulin and Elizabeth Stevens, their brothers William and George Stevens, and Ann's husband and child.
The downturn in whaling led to the abandonment of the station about 1850, but the village was thriving and Howell embarked on a plan to establish a port by building the 130 ton Amazon, with which he traded between New Zealand, Tahiti and California. In 1853 he landed 500 sheep, the first in Southland; cattle were also imported.
Howell's activities were not all constructive. As a child he had known the punishment meted out to rabbit poachers. Determined that the settlement would enjoy this rich man's fare, he brought a number of rabbits from Australia and released them on an island near Jacobs River.
Howell had added to his original landholding by leasing land at Wreys Bush and Waimatuku. The Waimatuku lease was one of those cancelled in 1857 when the Otago Provincial Council, in an attempt to stimulate land sales, offered for sale 600,000 acres outside the designated hundreds, without the normal requirement that money should be spent on improvements. Pastoralists such as Howell feared that the money raised would be spent in districts other than their own and that the policy would eventually inflate land prices. In March 1857 Howell attended a public meeting which petitioned the provincial government for separation, and gave the largest contribution to a subscription fund set up for this purpose. The prize of provincial independence was obtained in 1861.
Jacobs River was proclaimed as the town of Riverton in 1858, and in 1862 it was declared a port of entry. Treacherous channels in the harbour made navigation difficult, and Howell's efforts to have a breakwater constructed led to his election to the Southland Provincial Council in 1862. His efforts on behalf of Riverton were unsuccessful as the council adopted a rival plan for construction of a port at Stanley, New River (Ōreti River). Howell was also involved in the fight to build a road from Riverton to Kingston on Lake Wakatipu, as a supply route to the goldfields and the burgeoning town of Queenstown.
By 1869, sickened by the provincial council's wasting money on impractical schemes and having sold Wreys Bush with its 7,000 sheep and 300 cattle, Howell retired from political life and took his wife and family to live at Garston, near Kingston. In January 1874 two of his sons drowned and his health began to fail. The management of Fairlight station at Garston was handed over to his nephew, and the family returned to Riverton. Howell decided on a trip to Sydney, in the hope that this would improve his health, and, accompanied by his son Thomas, left Bluff on the steamer Tararua in April. He died at Sydney on 25 May 1874. At his death he held some 100,000 acres of leasehold land and 1,000 acres of freehold land, together with 40,000 sheep and 1,000 cattle, in the Wakatipu area, besides extensive landholdings in the Riverton area.