The fast food chain said it hoped the move would help restore a "small but important sense of normalcy".
There will be a phased reopening over the next several months in Kyiv and western Ukraine in areas deemed safe, the burger giant said.
McDonald's had more than 100 restaurants in Ukraine before the conflict started.
The company has continued to pay wages to more than 10,000 staff since then.
"We've spoken extensively to our employees who have expressed a strong desire to return to work and see our restaurants in Ukraine reopen, where it is safe and responsible to do so," senior vice president Paul Pomroy said in a message posted on the firm's website.
"In recent months, the belief that this would support a small but important sense of normalcy has grown stronger. And Ukrainian officials have advised that businesses resuming operations will support the local economy and the Ukrainian people."
The company said it was working with suppliers and contractors to ensure the restaurants were ready for reopening.
McDonald's also suspended operations in Russia in March, and in May sold most of its Russian restaurants to a local licensee.