Smolka began his amateur career in 2010 and was able to achieve a 2-1 record in his first year of competition, also winning the X-1 amateur 135 lb. title. He would take nearly a year off before turning professional in 2012. He would pick up wins under the Destiny MMA and King of the Cage banners before moving on to the PXC promotion in late 2012. He would win all four fights he had with PXC and would leave the promotion as the flyweight champion.
In late 2013, Louis was signed by the UFC and was slated to make his promotional debut against Alptekin Ozkilic at UFC Fight Night 35 on January 15, 2014. Smolka was able to come out with a unanimous decision victory.
Smolka later faced Chris Cariaso on May 10, 2014 at UFC Fight Night 40. Smolka lost the fight via split decision.
Smolka faced Richie Vaculik on November 8, 2014, at UFC Fight Night 55. He won the fight via knockout in the third round, finishing him with a side kick to the face and swarmed on Vaculik til the fight was stopped. The win also earned Smolka his first Performance of the Night bonus award.
Smolka faced Neil Seery on July 11, 2015 at UFC 189. He won the fight by unanimous decision.
Smolka faced Patrick Holohan on October 24, 2015 at UFC Fight Night 76 in the main event. After a back and forth first round featuring creative maneuvers by both men, Smolka was able to establish top position on Holohan midway in round two and deliver a series of shots, prompting Holohan to give up his back. Smolka was then able to lock in the rear-naked choke and secure the victory.
Smolka next faced Ben Nguyen on July 13, 2016 at UFC Fight Night 91. He won the fight via TKO in the second round and was awarded a Performance of the Night bonus.
Smolka was expected to face Sergio Pettis on October 1, 2016 at UFC Fight Night 96. However, Pettis pulled out of the fight citing a minor injury and was replaced by promotional newcomer Brandon Moreno. Smolka lost the fight via submission in the first round.
Smolka faced Ray Borg on December 30, 2016 at UFC 207. At the weigh-ins, Borg missed weight for the bout, coming in at 129.5 pounds. As a result, he was fined 30% of his fight purse, which went to Smolka, who agreed to take a catchweight bout. Smolka lost the fight by unanimous decisioin.
Smolka faced Tim Elliott on April 15, 2017 at UFC on Fox 24. He lost the fight by unanimous decision. Both participants were awarded Fight of the Night for their performance.Pacific Xtreme Combat
Pacific Xtreme Combat Flyweight Championship (One time)
Ultimate Fighting Championship
Performance of the Night (Two times) vs. Richie Vaculik, Ben Nguyen
Fight of the Night (One time) vs. Tim Elliott