"I cannot put into words the depth of sadness I feel right now at hearing of Don's passing," Urban wrote in an Instagram post.
The post that Urban shared included a video of the two men singing together.
In a later post, the "Blue Ain't Your Color" singer shared a picture of himself with Gentry alongside a brief memorial.
"My prayers are with all the Gentry family today. Go rest high, T Roy," Urban wrote.
It was revealed earlier today that Gentry died after a helicopter he was riding in crashed.
Details have been scarce, but it was reported that the 50-year-old singer and another unidentified person died when the aircraft crashed sometime after noon on Friday.
Troy Gentry was one-half of the Montgomery Gentry duo, alongside his friend Eddie Montgomery.
Gentry's death was very tragic and several of his country music peers have come out to mourn his loss.
Singer Maren Morris shared the news with her Twitter followers.
"Horrible. My thoughts are with his family," Morris tweeted.0comments
"So sad... Prayers are with you @mgunderground. #RIP Troy Gentry," Lindsay Ell tweeted.
"My heart goes out to the family and friends of Troy Gentry. We are all incredibly sorry to hear about your loss. Your music will live on," rising country music star Chase Bryant said.