The grown-up child star reportedly turned down an invite to perform at Trump's inauguration celebrations in Washington, D.C. and now she's planning to join activists at a rally in her native Wales on Saturday (21Jan17).
Announcing the news on Twitter, she wrote: "I will be at the women's March in Cardiff tomorrow... Women's marches across the UK: what you need to know..."
She then posted a link to a guide listing all the 14 planned Saturday protests across Britain.
The Cardiff demonstration will begin at the city's Aneurin Bevan statue at 1pm local time.
Official marches will also take place in Bangor, Wales, Belfast, Northern Ireland, and Lancaster, Leeds, Southampton, Liverpool, London, York, and Manchester in England.
There is also a star-studded march planned for Washington, D.C. featuring Madonna and Katy Perry, while Chelsea Handler and filmmaker Ava DuVernay will lead a sister protest at the Sundance Film Festival in Park City, Utah.
Many protests are also planned across America.
Trump was inaugurated as the 45th President of the United States on Friday (20Jan17).
Church revealed Trump's aides asked her to sing at his inauguration in Washington, D.C. - and she turned them down flat.
"@realDonaldTrump Your staff have asked me to sing at your inauguration, a simple Internet search would show I think you're a tyrant. Bye," the opera star tweeted, along with four poop emojis.
Fellow Brit Rebecca Ferguson also declined Trump's invitation to perform after she was told she wouldn't be allowed to sing Billie Holiday's 1939 protest song Strange Fruit.