The 11 trade unions affiliated to the Labour Party published a statement of support with the trans and non-binary community.
In a statement published on social media, the Labour Unions said: "Trans rights are human rights, and trans rights are workers' rights.
"We in the trade union movement will do all we can to stand up for our trans members and all our trans siblings, to protect them from persecution, harassment and attack."
"The government must act now to protect all trans people, to make sure their rights are protected, expanded and upheld in our workplace and communities," the statement continued.
The Musicians' Union has been affiliated to the Labour Party since 1943. Other affiliated unions include Unite, Unison, GMB and the Fire Brigades Union (FBU).
The statement follows a decision not to send a delegation to Labour Women's Conference by five affiliated unions; the Musicians' Union, Unison, Aslef, USDAW and the Communications Workers Union (CWU).