This is a list of by-elections for the New South Wales Legislative Assembly. A by-election may be held when a member's seat becomes vacant through resignation, death or some other reasons. These are referred to as casual vacancies.Brackets around a date (D/M/Y) indicate that the candidate was unopposed when nominations closed or that, as a result of an appeal against an election result, the sitting member was replaced by the appellant. These candidates were declared "elected unopposed" with effect from the date of the closing of nominations or appeal decision, and there was no need to hold a by-election.
By-elections which resulted in a change in party representation are highlighted as: Gains for the Labor Party and its splinter groups in red; for the Liberal Party and its predecessors in blue; for the National Party and its predecessors in green; for independents and minor parties in grey; for the Free Trade Party in yellow and for the Protectionist Party in cyan.
Fifty-eighth Legislative Assembly 2023–2027
== Fifty-seventh Legislative Assembly 2019–2023 ==
Fifty-seventh Legislative Assembly 2019–2023
== Fifty-sixth Legislative Assembly 2015–2019 ==
Fifty-sixth Legislative Assembly 2015–2019
== Fifty-fifth Legislative Assembly 2011–2015 ==
Fifty-fifth Legislative Assembly 2011–2015
== Fifty-fourth Legislative Assembly 2007–2011 ==
Fifty-fourth Legislative Assembly 2007–2011
== Fifty-third Legislative Assembly 2003–2007 ==
Fifty-third Legislative Assembly 2003–2007
== Fifty-second Legislative Assembly 1999–2003 ==
Fifty-second Legislative Assembly 1999–2003
== Fifty-first Legislative Assembly 1995–1999 ==
Fifty-first Legislative Assembly 1995–1999
== Fiftieth Legislative Assembly 1991–1995 ==
Fiftieth Legislative Assembly 1991–1995
== Forty-ninth Legislative Assembly 1988–1991 ==
Forty-ninth Legislative Assembly 1988–1991
• Although the Vaucluse by-election was set for 18 June 1988, Michael Yabsley was declared elected unopposed on the close of nominations on 6 June. == Forty-eighth Legislative Assembly 1984–1988 ==
Forty-eighth Legislative Assembly 1984–1988
== Forty-seventh Legislative Assembly 1981–1984==
Forty-seventh Legislative Assembly 1981–1984
== Forty-sixth Legislative Assembly 1978–1981==
Forty-sixth Legislative Assembly 1978–1981
== Forty-fifth Legislative Assembly 1976–1978==
Forty-fifth Legislative Assembly 1976–1978
== Forty-fourth Legislative Assembly 1973–1976==
Forty-fourth Legislative Assembly 1973–1976
== Forty-third Legislative Assembly 1971–1973==
Forty-third Legislative Assembly 1971–1973
== Forty-second Legislative Assembly 1968–1971==
Forty-second Legislative Assembly 1968–1971
== Forty-first Legislative Assembly 1965–1968==
Forty-first Legislative Assembly 1965–1968
== Fortieth Legislative Assembly 1962–1965==
Fortieth Legislative Assembly 1962–1965
== Thirty-ninth Legislative Assembly 1959–1962==
Thirty-ninth Legislative Assembly 1959–1962
== Thirty-eighth Legislative Assembly 1956–1959==