Porter originally committed to the University of Washington in July 2016. However, his father, Michael Porter Sr., was subsequently hired as an assistant coach for the University of Missouri, and Porter Jr. eventually decided to decommit from Washington and join his father at Missouri. He committed to play for the Tigers on March 24, 2017, joining his younger brother, Jontay Porter, who had also reclassified from the class of 2018.

Unfortunately, Porter Jr.'s college career was hampered by injury. He was injured in the first half of the season opener against Iowa State and was expected to miss the remainder of the 2017-18 season due to a lower back injury that required surgery. However, he was cleared to practice with Missouri again in February 2018 and officially returned to action on March 8, 2018, in the quarterfinals of the SEC tournament.

Although he played in the first round of the 2018 NCAA Division I men's basketball tournament, where the team lost to Florida State, Porter Jr. mainly came off the bench in both the tournament and the SEC tournament as a precaution. On March 27, 2018, Porter Jr. announced his intention to forgo his final three seasons of collegiate eligibility and declared for the 2018 NBA draft.

Since then, Porter Jr. has been making waves in the NBA, playing for the Denver Nuggets and showcasing his exceptional talents on the court. With his impressive size, speed, and athleticism, Porter Jr. has quickly established himself as a key player on the Nuggets roster and is expected to continue making headlines in the years to come.