Despite playing without Russell Westbrook, out with a strained left quad, the Wizards rode a balanced scoring attack that featured six players in double figures.
Devin Booker came up one point short in his personal duel with Beal, totaling a team-high 33 points for the Suns.
Washington never trailed, using a 20-10 game-opening run to quickly take a double-digit advantage. Beal did half the scoring in the initial burst.
Beal finished the first quarter with 13 points, just two fewer than the Suns, as the Wizards ran up a 29-15 advantage.
Washington built its first 20-point lead at 43-23 on a 3-pointer by Davis Bertans with 7:14 left in the second quarter and went into halftime holding a 68-42 advantage.
Phoenix got no closer than 21 in the second half.
Beal shot 12-for-22 en route to his sixth 30-point outing of the season. He also found time for a team-high nine assists and eight rebounds.
Bertans finished with 18 points off the bench for Washington, while Raul Neto had 16, Robin Lopez and Garrison Mathews 11 apiece and Rui Hachimura 10.
Lopez added a game-high 11 rebounds.
The 107 points allowed by Washington was a season low. The Wizards had lost three straight, giving up an average of 128.3 points in those games.
Booker went 11-for-21 for the Suns, who were outshot 52.2 percent to 44.8 percent.
Chris Paul notched a double-double for the Suns with 14 points and a game-high 11 assists, while Mikal Bridges chipped in 14 points and Dario Saric 13.
The 128 points allowed were 11 more than the Suns had permitted in any previous game this season.