He played college basketball for the Michigan Wolverines and spent his first professional season as a two-way contract player with the Miami Heat and their G League affiliate, the Sioux Falls Skyforce.

[3] Walton had a breakout season as a junior, that included posting 47 points and 12 rebounds against Crockett High School on March 9, 2012, and a quadruple-double against Cesar Chavez Academy on January 31, 2012.

[5] At Chandler Park Academy, he was the runner-up for the 2013 Mr. Basketball of Michigan award by a 2,130–2,086 margin to Iowa State signee Monté Morris but had one more first-place vote.

[21][22] On January 9 against Nebraska, Walton contributed key baskets at the end of each half in a one-point victory, giving Michigan its first five-game win streak since the 2013 NCAA tournament.

[38] Walton was named along with Big Ten point guards Yogi Ferrell and Melo Trimble to the 36-man Bob Cousy Award Preseason Watch List.

The 10 points included two three-pointers that tied the score at 42 and gave Michigan a 45–42 lead and 4 free throws in the final minute.

[50][51] On January 24, Walton scored a team-high 17 points and hit a three-pointer with 1.3 seconds to go against (AP #6/Coaches #5)[52] Wisconsin to tie the game and send it to overtime, but Michigan eventually lost.

[53] On January 27, Walton was removed from the lineup prior to the game due to a sore toe as Michigan defeated Nebraska.

[63] In the subsequent game on December 5 against Houston Baptist, Caris LeVert started in his place at point guard while he sat out.

[64][65] On December 15 against Northern Kentucky, Walton returned from the ankle injury that had sidelined him for three games, and posted 16 points, one rebound, one assist and one steal.

[66][67] On December 19 against Youngstown State, Walton posted 10 points, 11 rebounds and 13 assists, becoming the fifth player in school history to record a triple-double.

[83][84] The record lasted 5 years until Mike Smith posted 15 for the Wolverines in the 2021 Big Ten men's basketball tournament.

[89][90] Six steals broke a Michigan single-NCAA tournament game record shared by Mitch McGary (2013), Ricky Green (1977) and Tom Stanton (1977).

[93] In the championship game of the 2016 2K Sports Classic held at Madison Square Garden on November 18, Walton made a career-high seven three-point shots and scored 23 points as Michigan defeated SMU 76–54.

[104] On March 5, Walton posted 18 points, 5 steals, and set the Michigan single-game assists record with 16 against Nebraska in the final regular-season game of his senior year,[105][106][107] surpassing Grant who had twice totalled 14.

[112] In the March 11 semifinal of the Big Ten tournament against Minnesota, Walton posted a career-high 29 points including a perfect 10-for-10 on his free throws as well as a game-high 9 assists to lead Michigan to an 84–77 victory.

[116] During the Big Ten tournament, Walton averaged 20.5 points, 6.3 assists, 4.8 rebounds and 1.8 steals while shooting 22-for-23 from the free throw line.

[119] In the first round of the 2017 NCAA Division I men's basketball tournament, Walton posted 26 points and 11 assists in a 92–91 victory over Oklahoma State.

[126] Walton finished second in minutes played (34.8), free throw percentage (87.6%) and assists/turnover ratio (2.9) in the Big Ten for the season.

[140][141] With Dion Waiters absent and Rodney McGruder sidelined,[141] Walton was active on November 6 against the Golden State Warriors, when he made his NBA debut, posting one defensive rebound in one minute of play.

[142] Walton converted 2 free throws on November 19 against the Indiana Pacers,[143] and he posted his first NBA field goal (a three-point shot) on December 18 against the Atlanta Hawks.

[151] On February 12, 2019, Walton, whose playing time had started declining since December, left Žalgiris by terminating his deal with mutual agreement.

[158] Walton remained deep on the Clippers bench early in the season as the team used Jerome Robinson and Terance Mann in the backup point guard role.

On December 8, with JaMychal Green hobbled and Patrick Patterson, Rodney McGruder and Landry Shamet sidelined Walton played his first meaningful minutes, posting a career-high 7 points and contributing to a win against the Washington Wizards.

[160] On January 4, 2020, with Paul George joining Patrick Beverley on the sidelines, Walton made his first NBA start against the Memphis Grizzlies.

[165] After spending pre-season with the Philadelphia 76ers,[166] Walton moved to France in December 2020 to play for ASVEL until the end of the 2020–21 Pro A season.

[170] On January 1, 2022, he delivered a game-winning assist in overtime against the San Antonio Spurs that went between the defender's (Jakob Pöltl) legs to Saddiq Bey.

[177] In March 2023, he helped the Kings win the NBL championship with a 3–2 grand final series victory over the New Zealand Breakers.

[178] Walton joined the Zhejiang Lions of the Chinese Basketball Association for the 2023–24 season and averaged 12.6 points and 5.1 assists per game in 42 appearances.

[181] On January 14, 2025, he was ruled out for the rest of the season after suffering another hamstring injury three days earlier in a game against the Brisbane Bullets.