The American sank four of five shots from three-point range and all seven of his free throws while contributing six assists, two steals and two blocked shots.
"Spectacular," said Suns coach Frank Vogel. "He's one of the best players in the world. That's why we were excited to get him in Phoenix.
"Played great defense. Came out sharing the basketball. It's about being aggressive and reading the defense. He did a great job with that."
Beal, the third overall pick in the 2012 NBA Draft, spent 11 seasons with the Wizards, averaging 22.1 points a game for a perennial doormat, reaching the play-offs only once in his time with Washington.
The Wizards played a video tribute to Beal in his first visit since being traded last June while fans gave him a standing ovation.
"Tonight was awesome," Beal said. "It was a good separation. No hard feelings."
Kevin Durant added 18 points for the Suns, who improved to 29-21 while sinking the Wizards to 9-40.
Meanwhile Boston's Jayson Tatum scored 34 points, grabbed eight rebounds and passed off seven assists to lead the NBA-best Celtics over visiting Memphis 131-91.
Latvian forward Kristaps Porzingis added 26 points for the Celtics, who improved to 38-12.
Kawhi Leonard scored 25 points and grabbed 11 rebounds to lead the Los Angeles Clippers in a 103-95 victory at Miami - the Clippers' 25th triumph in 30 games to reach 33-15.
James Harden added 21 points and 11 assists and Paul George had 15 points for the Clippers, while Jimmy Butler led the Heat with 21 points.
Finland's Lauri Markkanen scored 21 points to lead seven Utah players in double figures who powered the Jazz over visiting Milwaukee 123-108.
Greek star Giannis Antetokounmpo led the Bucks with 33 points, 13 assists and seven rebounds while Bobby Portis added 27 points for Milwaukee, which fell five games back of East leader Boston.
Reigning NBA champions Denver, led by 29 points from Nikola Jokic, dispatched visiting Portland 112-103, pulling the Nuggets within a half-game of the West co-leaders.
Josh Giddey netted 24 points to lead five Oklahoma City players with 20 or more points as the host Thunder outlasted Toronto 135-127.
Shai Gilgeous-Alexander had 23 points, 14 assists and nine rebounds while Luguentz Dort and Chet Holmgren each added 22 points for the Thunder, who matched Minnesota atop the Western Conference at 35-15.
Finch is All-Star coach
Minnesota's Chris Finch earned the Western Conference All-Star head coaching job when the Timberwolves defeated visiting Houston 111-90 to take the conference's best record as of Sunday including tie-breakers.
It's his first time as an All-Star head coach and the first for a Minnesota coach since Flip Saunders in 2004.
Anthony Edwards led the T-Wolves with 32 points while Frenchman Rudy Gobert contributed 17 points and a game-high 13 rebounds.
Germany's Franz Wagner scored 38 points on 17-of-25 shooting, four of seven from 3-point range, to lead the Orlando Magic to a 111-99 victory at Detroit.
Charlotte rookie Brandon Miller scored a season-high 35 points but it was in a losing cause as the visiting Indiana Pacers beat the Hornets 115-99.
Cameroonian forward Pascal Siakam had 25 points, eight rebounds and nine assists to spark the Pacers while Aaron Nesmith added 22 points.
