Ed Sheeran, the Rolling Stones and Coldplay also signed the letter to the culture secretary warning of the impact of Covid-19 on venues and musicians.
It says the music industry faces "mass insolvencies", with gigs and festivals unlikely to return until 2021.
The organisers said there had already been "hundreds of redundancies".
Job losses have been reported across venues, agencies and promoters, they said.
The letter to Oliver Dowden reads: "With no end to social distancing in sight or financial support from government yet agreed, the future for concerts and festivals and the hundreds of thousands of people who work in them looks bleak."
It calls for a "clear, conditional timeline" for reopening venues without social distancing, as well as financial support and a VAT exemption on ticket sales.
Eric Clapton, Beverley Knight, Little Mix and Skepta are among the other stars to have added their names.
In an accompanying statement, Dua Lipa said she was "proud" to have worked her way up through small clubs, theatres, arenas and festivals.
She said: "But the possibility for other emerging British artists to take the same path is in danger if the industry doesn't receive much needed government support in the interim period before all the various venues, festivals and promoters are ready and able to operate independently again."
Former Oasis frontman Gallagher added: "Amazing gigs don't happen without an amazing team behind the stage, but they'll all be out of jobs unless we can get back out there doing what we love."