Edinburgh-based Harry Potter creator Ms Rowling’s Lumos Foundation is raising money to provide food and hygiene and medical kits to youngsters affected by the conflict, as well as helping to support their evacuation from the country.
Money raised will also go to providing psychological support to children impacted by the conflict, and supporting families and foster carers.
Ms Rowling, 56, wrote on Twitter: “I will personally match donations to this appeal, up to £1m. Thank you so, so much to all who’ve already donated, you’re enabling @lumos to do crucial work for some of the most vulnerable children in Ukraine.”
Lumos, which was co-founded by Rowling in 2005, has been operating in the Zhytomyr region, which lies to the west of the Ukrainian capital of Kyiv.
It estimates there are more than 1,500 children trapped in orphanages there, with thousands more at risk of displacement and family separation.
In response to a Twitter follower who pointed out that children in countries including Afghanistan and Yemen are also living in poverty – and suggested she should also donate to them – Ms Rowling wrote: “I support children in all of those places through my separate charitable trust, but @lumos is a charity specifically for children in institutions and during wars, those children become even more vulnerable. Hence the current appeal!”