[1] He won a national championship with Brewster Academy in 2012 after achieving star status with his high school team.

Mary High School in Akron, Ohio from 2007 to 2010, before transferring to Brewster Academy in August 2010 for his senior year.

[7] On March 24, 2014, Sampson announced his intentions to enter the 2014 NBA draft and forgo his final two years of college eligibility.

[15] The next day, he made his debut with the Nuggets in a 114–110 loss to the Sacramento Kings, recording one rebound and one steal in fourteen minutes off the bench.

38 overall pick in the 2018 NBA G League Draft, Mike Amius from Iowa Wolves for the returning rights to Jarell Eddie and Jaylen Johnson,[25] and later on November 9, 2018, the Windy City Bulls acquired Sampson.

[26] On December 19, 2018, Shandong Golden Stars of the Chinese Basketball Association (CBA) was reported to have signed Sampson in replacing injured Donatas Motiejūnas.

[32] On April 21, 2021, Sampson was suspended for one game without pay for headbutting Patty Mills during an altercation between the Pacers and the San Antonio Spurs.

[33] On September 27, 2021, Sampson signed a 2-year deal with Virtus Bologna of the Italian Lega Basket Serie A (LBA); the team also plays in the EuroCup.

[34] After having ousted Lietkabelis, Ulm and Valencia in the first three rounds of the playoffs, on 11 May 2022, Virtus defeated Frutti Extra Bursaspor by 80–67 at the Segafredo Arena, winning its first EuroCup and qualifying for the EuroLeague after 14 years.

[35] However, despite having ended the regular season at the first place and having ousted 3–0 both Pesaro and Tortona in the first two rounds of playoffs, Virtus was defeated 4–2 in the national finals by Olimpia Milano.