Following Russia's invasion of Ukraine in February, Yastremska and her 15-year-old sister Ivanna spent two nights sheltering in an underground car park.
Eventually, she and her sister were sent to France by their parents where they've been safely housed.
The world No.128 then took part in the Lyon Open this week and worked her way to the final following wins against Ana Bogdan, Cristina Busca, Jasmine Paolini and Sorana Cirstea.
That set up a climactic final with China's Zhang Shuai, but despite winning the first set, Yastremska fell to a 3-6 6-3 6-4.
But despite falling short in the final, Yastremska can be extremely proud of her efforts after such a disturbed few weeks.
Following the match, the 21-year-old draped herself in a Ukrainian flag and vowed to donate all prize money to help her home nation.
"The prize money I earned here I'm going to give to the Ukrainian foundation to support the Ukraine.
"And if Ukrainian people are watching me, I want to say you guys are so strong, you have an amazing spirit.
"I try to fight for Ukraine. I want to say thanks to every single person from Ukraine for standing by the Ukraine and showing people that we have a really strong spirit."
Tournament winner and world No.64 Zhang said, "Big congrats to Dayana and your team, working so hard. I know it is a big tough time for you but you are a fighter."