However, due to a stomach virus, Morris only played for five minutes, scoring three points and grabbing two steals before Channing Frye took over the power forward position in a 91–88 victory.

On March 25, he recorded a then career-high 22 points to tie Marcin Gortat as the game's leading scorer in a 108–83 victory over the Cleveland Cavaliers.

After scoring a then season-high 16 points against the defending champion Miami Heat, Morris made his first start of the season on November 21, 2012.

Morris topped his season high in points by three and tied Marcin Gortat with seven rebounds in a victory over the Portland Trail Blazers.

[13] On February 21, 2013, Morris' twin brother Marcus was traded to the Phoenix Suns, reuniting them after two years of playing for separate teams.

[17] Morris was named the Western Conference Player of the Week for the November 4–11, 2013 period after averaging 22.8 points, 8.0 rebounds, 2.0 steals and leading the league for field goal percentage (.698).

[21] He and Marcus, alongside teammates Goran and Zoran Dragić, all briefly played together for the Suns during the fourth quarter of their 112–96 victory over the Philadelphia 76ers on January 2, 2015.

[28] During the fourth quarter of the Suns' December 23 game against the Denver Nuggets, Morris threw a towel in the direction of Hornacek as he was heading to the bench.

[29] The following day, Morris was suspended for two games for conduct detrimental to the team,[30] and was later labelled one of Arizona's biggest sports villains by AZCentral.com.

[31] Following an injury to teammate Alex Len in early January, Morris was reinserted back in the rotation to help fortify the frontcourt.

[34] In his final game with the Suns on February 10 against the Golden State Warriors, Morris and teammate Archie Goodwin got into a physical altercation on the bench and were seen arguing during a timeout.

[35] On February 18, 2016, Morris was traded to the Washington Wizards in exchange for DeJuan Blair, Kris Humphries and a 2016 Top–9 protected first round draft pick.

[36] The next day, he made his debut for the Wizards in a 98–86 victory over his brother's team, the Detroit Pistons, recording six points and two rebounds in 22 minutes.

On April 16, 2017, Morris scored 21 points in his NBA playoff debut as the Wizards defeated the Atlanta Hawks 114–107 in Game 1 of their first-round series.

[42] On January 3, 2019, Morris was ruled out for six weeks following a bout of neck and upper back stiffness that led to him being diagnosed with transient cervical neurapraxia.

[48] Morris was signed by the Los Angeles Lakers on February 23, 2020, using the $1.75 million disabled player exemption they were granted to replace DeMarcus Cousins.

In the second half of Game 3, Lakers head coach Frank Vogel countered the Rockets small-ball lineup by starting Morris in place of JaVale McGee and moving Anthony Davis to center.

[61][62] On February 2, 2025, Morris, alongside Luka Dončić and Maxi Kleber were traded to the Los Angeles Lakers in exchange for Max Christie, Anthony Davis and a 2029 first-round pick.

[71] The Morris twins helped create the Family Over Everything Foundation, an organization that assists members of under-served communities in Philadelphia and other cities.