Hoenig was born in Camperdown on 21 April 1953, and at age five moved with his parents from Maroubra to a house in King Street, Eastlakes. Hoenig received his education at local schools, Eastlakes Public School, Daceyville Public School, and JJ Cahill Memorial High School in Mascot.^[5]

With a university education beyond his family's financial resources, at age 19 Hoenig was employed in the Petty Sessions Branch of the Attorney General and Justice Department, and with the removal of university fees by the Whitlam Labor Government, he enrolled to study law at the Solicitors’ Admission Board (now the Legal Profession Admission Board) and was admitted with a Diploma in Law to practise law in New South Wales in 1980. Hoenig worked as an articled clerk, and then as a solicitor in the Public Solicitor's Office, practicing litigation and criminal law. In 1987, he was appointed as a Public Defender for the State of New South Wales, a role he held until being elected to parliament in 2012.^[6][7]

Hoenig was a practising barrister and public defender, who acted as the counsel assisting the inquiry into the death of Dianne Brimble, where he made recommendations that up to three of the persons assisting the inquiry could face prosecution. He defended David Dinh, who was accused of killing New South Wales MP John Newman. Dinh was acquitted by a jury.^[8]

After being elected as an alderman of the Municipality of Botany in September 1980, Hoenig was elected mayor in 1981 and became the first popularly elected mayor of the council in 1983, with 85% of the vote.^[9][10] He was re-elected mayor in 1987 (unopposed), 1991 (80%), 1995 (88%), 1999 (unopposed), 2004, and 2008.^{[11][12][13][14]} Hoenig was mayor when Botany was proclaimed the City of Botany Bay on 11 May 1996.

During his time as mayor, Hoenig campaigned on various issues such as heritage protection, where he supported the establishment of the Botany Historical Trust in 1994 and commissioned the Botany Bay Heritage Study in 1996, as well as the non-expansion of both the Botany Port and Sydney Airport.^[15][16] He did not seek re-election at the 2012 local government elections.^[17]

Hoenig was preselected as the Labor candidate for 25 August 2012 Heffron by-election in the New South Wales Legislative Assembly, following the parliamentary resignation of former Premier and state Labor MLA Kristina Keneally. Hoenig drew top spot on the ballot paper, with three other candidates from the CDP, Greens and Democrats.^[3][18] Hoenig won with a 60 percent primary and 70 percent two-candidate-preferred vote.^[19]

On 11 June 2021 Hoenig was appointed as manager of opposition business by leader of the opposition Chris Minns^[20]

Hoenig's parents Ernest and Edith migrated to Australia after World War II. Edith was a Holocaust survivor born in Czechoslovakia and Ernest was born in Austria. Hoenig married Christine Stamper on 27 June 1985 at St Bernard's Roman Catholic Church, Botany, and the marriage produced two sons; Benjamin and Matthew.^[21] Hoenig is a member of the Maroubra Synagogue.^[22]

Hoenig is a supporter of the South Sydney Rabbitohs rugby league club, having served as a board director in 1999, and was a prominent opponent at the time of the National Rugby League's efforts to remove the club from the competition and proposals to merge it with other clubs.^[23][24][25]