Diana Gamage (born 18 December 1965) is a Sri Lankan politician and businesswoman. She was a former State Minister of Tourism and Member of Parliament.

Gamage was appointed to the Parliament of Sri Lanka from the National List of the Samagi Jana Balawegaya following the 2020 Sri Lankan parliamentary election.^[1] In 2021 she switched her political affiliation to the Sri Lanka Podujana Peramuna, then ruling party of Sri Lanka.^[2]

Her right to serve in Parliament was challenged by a Writ petition filed by the social media activist Oshala Herath who had unsuccessfully contested the 2020 parliamentary election from the United National Party, on the basis that Gamage held British citizenship. Herath had claimed that Gamage had gained British citizenship in 1998 and not gained dual Sri Lankan citizenship, while Gamage claimed that she had renounced her British citizenship in 2014. The Court of Appeal of Sri Lanka set aside Herath's petition in 2023. On 8 May 2024, following an appeal to the Supreme Court of Sri Lanka, the court set aside the judgement of the Court of Appeal and disqualified Gamage from holding a seat in Parliament on the basis that she did not hold valid citizenship of the country, since she failed to submit a certificate of citizenship and found that she had returned to Sri Lanka on a British passport. The Samagi Jana Balawegaya party named Mujibur Rahman as her replacement.^[3][4][5][6]