Sampo started his professional career in 2009. He fought mainly for Missouri-based promotions as Fight Me MMA, Wright Fights and Rumble Time Promotions. He is now a high school science teacher at Francis Howell High School in St. Charles county, Missouri.

Sampo was expected to face Rafael de Freitas on September 14, 2012, at Legacy FC 14.^[5] However, instead he faced Antonio Banuelos. He won via unanimous decision (30–27, 30–27, 30–27) .^[6]

Sampo faced Olympic medallist and Bellator MMA veteran Alexis Vila on January 19, 2013, at CFA 9: Night of Champions for the inaugural flyweight title. Sampo defeated Vila via submission due to a guillotine choke in the fifth round and became the CFA flyweight champion.^[7]

Sampo defended his title once against Sam Thao on October 12, 2013, at CFA 12: Sampo vs. Thao. He won via unanimous decision (49–46, 49–46, 49–46) after five rounds.^[8]

In November 2013, it was announced that Sampo had signed with the UFC.^[9]

Sampo made his promotional debut against fellow newcomer Ryan Benoit on November 30, 2013, at The Ultimate Fighter 18 Finale. Sampo won via submission due to a rear-naked choke and the performance earned both participants Fight of the Night honors, but Sampo was not eligible for the bonus due to missing weight.^[10][11]

Sampo faced Zach Makovsky on February 22, 2014, at UFC 170. Sampo had his first octagon defeat via unanimous decision (30–27, 30–27, 29–28).^[12]

Sampo faced promotional newcomer Paddy Holohan on July 19, 2014, at UFC Fight Night: McGregor vs. Brandao. He lost via submission due to a rear-naked choke in the first round.^[13]

Sampo faced Justin Scoggins on May 23, 2015, at UFC 187.^[14] Sampo lost the fight via unanimous decision.^[15] Subsequently, he was released from the promotion.^[16]

Sampo faced Dominic Mazzotta at Bellator 197 on April 13, 2018.^[17] He lost the fight by unanimous decision.

• Ultimate Fighting Championship
  • Fight of the Night (one time) vs. Ryan Benoit
• Championship Fighting Alliance
  • CFA flyweight title (one time)
  • One successful title defense
• Cage Championships
  • CC amateur bantamweight title (one time)^[18]
• Fight Matrix
  • 2012 Most Improved Fighter of the Year^[19]

• National Association of Intercollegiate Athletics^[20][21]
  • NAIA Wrestling National Championship All-Americanout of Lindenwood University (2005, 2006, 2007)
  • NAIA Wrestling National Championship 125 lb: Fourth place out of Lindenwood University (2006)
  • NAIA Wrestling National Championship 125 lb: Fifth place out of Lindenwood University (2005, 2007)
• Nevada Interscholastic Activities Association^[21][22]
  • Nevada State High School Wrestling 103 lb: Champion out of Pahranagat Valley High School (2001)
  • Nevada State High School Wrestling 112 lb: Champion out of Pahranagat Valley High School (2002)

^[18]