Ratification of the law of December last year did not meet quorum set so considered invalid.
Came into effect in February, these laws impose a life sentence for behavior that 'increases homosexual' or a 'promotion of homosexuality'.
Homosexual acts are illegal in Uganda that is conservative but the threat of a life sentence sparked fierce controversy over again.
Legislation signed Presiden Yoweri Museveni for the first time includes lesbians and same-sex marriage was also threatened with a life sentence.
Several donors, including the United States, to stop its aid since the Act is enforced.
And United States President Barack Obama warned the passing of the Act a setback for Uganda.
The latest decision of the Constitutional Court of Uganda can still be sued again in the Supreme Court but Kosiya Kasibayo, a state attorney, said no decision regarding the appeal.
BBC reporters in the capital Kampala, Catherine Byaruhanga, reported antihomoseksual Act supporters expressed anger over the decision of the Court.
They questioned whether the decision was related to President Museveni's visit to Washington next week for a summit of the United States and Africa.
