Justice Brereton will serve as deputy until July, when he will replace Justice Peter Johnson as chairperson.
In an announcement on Monday, Attorney-General Gabrielle Upton congratulated the new appointees and thanked outgoing chair Justice Johnson for his service.
"I am excited by the addition of two outstanding individuals to the body responsible for reviewing and shaping our legislative framework," Ms Upton said.
"I thank Justice Johnson for his significant contributions to the Law Reform Commission, which have included working on important references on sentencing and encouraging appropriate early guilty pleas," she added.
Tracy Howe is the CEO of the state’s Council of Social Service, which works to advance the interests of civil society in NSW, and was previously the CEO of Domestic Violence NSW.
Ms Howe sits on a number of NSW government bodies including the Domestic and Family Violence Council and the Premier's Council on Homelessness. She also serves as a member of the the Council of Australian Governments Advisory Panel on Reducing Violence against Women and their Children.
Justice Brereton worked as a barrister from 1987 until 2005, when he was appointed as a Supreme Court judge. He is a member of the Defence Force Discipline Appeal Tribunal and was appointed a Member of the Order of Australia (Military Division) in 2010.
He has held positions within the Army Reserve since 1994 and in 1995 was awarded the Reserve Force Decoration.