Thatch started his amateur MMA career on March 31, 2007 against Jesse Brown, which he won via second round submission. Thatch went undefeated as amateur in 2007 with a 3-0 record. He made his pro debut in June 2008 against Mike Crisman at Ring of Fire 32. Thatch won the fight via TKO 38 seconds into the fight.

Thatchthen faced Chris Holland at Ring of Fire 40, winning via KO in 19 seconds. Next for Thatch was a bout with Chidi Njokuani at Ring of Fire 41, which he won by TKO in the first minute. In his next fight, Thatch took on Patrick Vallee at Instinct MMA 2 on December 2, 2011, winning via TKO in 15 seconds. Thatch was named Bloody Elbow’s #3 welterweight prospect in their annual scouting report. Four months later, Thatch fought Jory Erickson at Instinct MMA 3. He won the fight by KO in 18 seconds. Thatch next faced Martin Grandmont at Instinct MMA 4 on June 29, 2012. He won the fight via submission in the first round.

On May 8, 2013, Thatch signed a multi-fight deal with the UFC.

Thatch faced Justin Edwards on August 28, 2013 at UFC Fight Night 27. He won the fight via TKO in the first round. The win earned him his first Knockout of the Night bonus award.

In his second UFC fight, Thatch faced Paulo Thiago at UFC Fight Night 32 on November 9, 2013. He won the fight via TKO in the first round, forcing Thiago to submit after landing a knee to the liver. With the win, Thatch extended his first round finish streak to ten.

Thatch was expected to face Jordan Mein on August 23, 2014 at UFC Fight Night 49, replacing an injured Thiago Alves. Subsequently, Thatch pulled out of the bout with Mein, citing a toe injury.

Thatch was expected to face Stephen Thompson on February 14, 2015 at UFC Fight Night 60. However, Thompson pulled out of the fight on January 30, citing a rib injury. Subsequently, Thatch faced former UFC Lightweight Champion Benson Henderson at the event. Thatch lost the back and forth fight via submission in the fourth round. Their performance earned both participants Fight of the Night honors.

Thatch was expected to face John Howard on July 11, 2015 at UFC 189. However, on June 23, Thatch was pulled from that bout in favor of a fight with Gunnar Nelson, as his scheduled opponent, John Hathaway, was forced out with an injury. Thatch lost the fight by submission in the first round after getting knocked down by Nelson.

Thatch next faced Siyar Bahadurzada on March 5, 2016 at UFC 196. He lost the fight via submission in the third round.

Thatch was expected to face Erick Silva on September 24, 2016 at UFC Fight Night 95. However, Thatch pulled out of the fight with an undisclosed injury and was subsequently replaced by Luan Chagas.

Thatch was expected to face Sabah Homasi on December 30, 2016 at UFC 207. However, Homasi pulled out of the fight, citing injury, and was subsequently replaced by promotional newcomer Niko Price. Thatch lost the fight by submission in the first round and was subsequently released from the promotion.