Wizards and Jason Richardson and Turkey's Hedo Turkoglu from the Phoenix Suns.
Lewis was sent to the Wizards for Arenas, a three-time All-Star who has been plagued by injuries and suspensions in recent years.
'Gilbert is a proven All-Star in this league and we're excited to add him to our team,' Magic president Otis Smith said. 'He is one of the top scoring guards in the game, he can create scoring chances for his teammates and he is as tough as they come.'
Carter, French forward Mickael Pietrus and Polish center Marcin Gortat were sent with a 2011 first-round pick and cash considerations to the Suns for Richardson, Turkoglu and forward Earl Clark.
'We're very excited to welcome these three players,' Smith said.
With Howard as their anchor, the Magic reached the NBA Finals in 2009 and the Eastern Conference finals a year ago. They got off to a 15-4 start this season but have lost five of their last six games entering Saturday's contest vs. Philadelphia.
Carter and Lewis both had been struggling. Carter, an eight-time All-Star, was averaging a career-low 15.1 points. Lewis, a two-time All-Star, was averaging 12.2 points - his lowest number in 10 years - while shooting just 42 percent from the field.
Smith has had an affinity for Arenas since both were with Golden State almost 10 years ago. The acquisition is a risky one, as Arenas has played just 68 games in the last four years due to knee problems and a 50-game NBA suspension last season for bringing guns to the team's locker room.
Arenas, who has three years and 62 million dollars remaining on his contract, has been healthy this season. Once the face of Washington's franchise, he saw his role reduced after the Wizards drafted John Wall and is averaging 17.3 points while shooting less than 40 per cent from the field.
'We envisioned a level of team success that we unfortunately were not able to achieve due to injuries (to Arenas) and other factors beyond our control,' Wizards president Ernie Grunfeld said.
Richardson joins his fourth team. In his 10th season, the former Slam Dunk champion is averaging 19.3 points and shooting 42 per cent from three-point range.
'Jason is a tremendous athlete who runs the floor, can shoot the ball and loves to compete,' Smith said.
Turkoglu was part of the Magic's 2009 Finals team but left as a free agent after that season. He has struggled on and off the court in Toronto and Phoenix but may be rejuvenated by a return to Orlando, where he thrived for five years, averaging nearly 16 points per game.
'We're obviously familiar with Hedo,' Smith said. 'He is a great shooter and is a player that has flourished in our system.'
The 6-10 Clark is in his second season and has played just 72 minutes this season.
In addition to Carter, the Suns get Pietrus, a solid defender averaging 6.7 points, and Gortat, who backed up Howard and averaged 4.0 points and 4.7 rebounds.
'Marcin addresses our need for more size, rebounding and defensive presence,' Suns president Lon Babby said. 'Vince and Mikael will be dynamic in our offense and improve our perimeter defense.'