Authorities deployed water-bombing planes, the national armed forces and hundreds of firefighters.
High winds and soaring temperatures have helped spread the fires in the Luhansk region, near areas held by Russian-backed separatist forces.
President Volodymyr Zelensky visited the area and promised compensation for those affected.
Temporary accommodation would be arranged for people who had lost their homes, he said, while up to 50 million hyrvnias ($1.9m; £1.5m) would be given out to support victims.
Towns including Vovche and Smolianynove were evacuated and more than 300 members of the state emergency services arrived to battle back the fires.
The governor of Luhansk region, Serhiy Haydar, posted on Facebook that he suspected the fires were the result of arson, although this is unconfirmed.
Fires "erupted quite strangely for us", he wrote. Officials had written to separatists nearby to ensure they were not attacked as they tackled the blazes but "they could not give any security guarantees", Mr Haydar alleged.
Luhansk is currently divided between Ukrainian control and that of the self-proclaimed Luhansk People's Republic (LNR) amid an ongoing conflict in the east of the country. More than 13,000 people have been killed so far.
Wildfires raged through Ukraine earlier this year, including near the abandoned Chernobyl nuclear plant. Thick smoke blanketed the capital Kyiv.
And earlier in July heavy flooding hit nearly 300 towns and villages in the west of the country. Climate change, illegal logging and deforestation have all been blamed.