[1] Throughout his high school career, McCollum worked at refining his shooting stroke; the successful effort was reflected in the 29.3 points per game he averaged during his senior season.

[1] By graduation, McCollum had become the leading scorer in Golden Eagles history, with 1,405 career points, and was named Gatorade Ohio Player of the Year for his final campaign, the 2008–09 season.

McCollum led the Mountain Hawks to the 2010 NCAA tournament, where he put up 26 points in a first-round loss to a top-seeded Kansas team.

His shooting percentages dipped to 39.9 percent from the field, as did Lehigh's record, and McCollum was edged out for conference Player of the Year honors by Mike Muscala of the Bucknell Bisons.

[6] On November 25, 2012, McCollum scored 26 points in a 91–77 win over Sacred Heart to pass Rob Feaster as the Patriot League's all-time leading scorer.

He signed his rookie scale contract with the franchise on July 11,[11] and he proceeded to play for them in the NBA Summer League, averaging 21 points and 4 rebounds per game.

[13] He was recalled by the Blazers on January 5 and made his NBA debut three days later, during which he notched 4 points as Portland beat the Orlando Magic, 110–94.

[18] Exercising their fourth-year team option on September 30, 2015, the Trail Blazers extended McCollum's rookie scale-contract through the 2016–17 season.

[17] In the season-opener on October 28, McCollum posted a career-high 37 points, scoring 22 of which in the first quarter alone, helping the Blazers defeat the New Orleans Pelicans, 112–94.

No Blazer had recorded numbers on par with McCollum's near triple-double in the last 29 years (Clyde Drexler posted 34 points, 11 rebounds, and 9 assists or more on five occasions.

)[21] McCollum was able to resume his starting shooting guard role on January 4 as Lillard was back on his feet, returned from injury.

[29] Only four days later, he posted 23 points, 10 rebounds, 3 assists, 3 steals, and a career-high 3 blocks as Portland beat the Denver Nuggets, 115–113, in an overtime contest.

[35]) On February 7, McCollum scored 32 points; the last two of which, on a runner from the top of the lane, clinched the 114–113 win over the Dallas Mavericks with 0.9 seconds left.

[38] McCollum missed the opener of the 2017–18 season due to a single-game suspension incurred when he left the bench area once during a preseason game.

[42] On January 1, to defeat the Chicago Bulls, 124–120, he scored 25 of 32 points after halftime, including the game-clinching basket with 56.5 seconds left in overtime.

[44] He joined Damian Lillard, Damon Stoudamire, Brandon Roy, Andre Miller, Clyde Drexler and Geoff Petrie as Trail Blazers to score 50 points or more.

[50] On January 22, he scored 31 points and made seven 3-pointers in a 123–114 loss to the Oklahoma City Thunder, thus passing Nicolas Batum (751) for fourth on the franchise's all-time 3-pointers list.

[56] In the deciding Game 7, he scored a game-high 37 points in a 100–96 win, including the game-sealing step back jumper with 15 seconds remaining, to help the Blazers advance to the Western Conference Finals for the first time since 2000.

[62] On August 7, 2021, McCollum was elected president of the National Basketball Players Association, succeeding Chris Paul who had served since 2013.

[66] Two days later, McCollum made his Pelicans debut, putting up 15 points, seven rebounds, and five assists in a 112–97 loss to the Miami Heat.

[67] On April 13, during the NBA play-in tournament, McCollum recorded 32 points, six rebounds, and seven assists leading the Pelicans past the San Antonio Spurs 113–103 and advancing New Orleans to the eight seed game.

He joined Anthony Davis, DeMarcus Cousins, and Tyreke Evans as the only players in Pelicans history to put up at least 40 points, eight rebounds, and eight assists in a game.

With the Pelicans losing in the play-in game against the Minnesota Timberwolves, this marked the first time that McCollum had missed the playoffs in his career.

[75][76] In a March 2020 episode of the podcast, McCollum was recording when he received news that the NBA was suspending the 2020 season due to the COVID-19 pandemic.

The Center aims to provide a safe and inspiring space for underserved youth to learn, explore, create, and grow.

[82] McCollum also helps foster local youths' interest in journalists through an initiative called CJ's Press Pass; it grants aspiring journalists access to postgame news conferences and provides them the opportunity to attend events with McCollum, to receive personalized mentorship from members of the media, and to have their work published.