In 1904, Jenner married a widow, Mrs Rosa Margaret Wight Rowe who was an accomplished singer and pianist. Mrs Rowe had a business in Marine Terrace as a Bookseller and Newsagent.
Jenner had many interests in Geraldton in the more than 50 years he lived there. He was on the Town Council for many years and many periods, especially in the 1920s. He was a member of the Church of England Christ Church Vestry, sang as tenor in the Choir, and was Choirmaster for many years. He also conducted Church Choirs in outlying districts such as Greenough, and the first surpliced choir in Day Dawn in 1901. Jenner was a Synodsman and represented Christ Church at Synods in Perth. Archbishop Riley used to stay in the Jenner home in Chapman Road (built 1910) on his visits to Geraldton.
His other interests were the Geraldton temperance Brass Band, where he played the tuba and was conductor for a time. Cricket was another passion, and he played cricket until well into his 80s.
Another interest was the Masonic Lodge, of which he was a member for 54 consecutive years. He was a Past Grand Master and also held Masonic Orders with the Rechabites and Oddfellows. Jenner was a teetotaller all his life.
During World War I, Jenner and his wife held many soirees, etc to help the War Effort in their lovely Chapman Rd house.
Jenner moved to Perth after the death of his wife in 1948. In Perth he continued playing cricket, visiting old and sick friends, singing in Church Choirs, Lodge membership, etc. All his life he was a robust, remarkably active man, very good natured, an optimist, always smiling. He loved life and enjoyed it to the full.
J.J. Jenner passed away in the Royal Perth Hospital on 11 January 1951. The funeral took place at Karrakatta Cemetery.