Johnson signed a one-year contract Monday with Greek club Panathinaikos, Eurohoops.net reports.
Johnson was waived by the Wizards on Friday, Adrian Wojnarowski of ESPN reports.
Johnson played 25 minutes and contributed six points (2-5 FG, 1-3 3Pt, 1-1 FT), three rebounds, two assists, one steal and one block Monday in the Wizards' 121-112 loss to the Pistons.
Johnson will be available to play Friday against Cleveland.
Johnson was traded from the Pelicans to the Wizards on Thursday in exchange for Markeiff Morris (neck) and a 2023 second-round pick, David Aldridge of The Athletic reports.
Johnson (coach's decision) failed to leave the bench Wednesday in the Pelicans' 98-94 loss to the Pistons.
Johnson went scoreless (0-1 FG, 0-1 3Pt) in seven minutes during Friday's 114-112 win over the Mavericks.
Johnson had three points (1-3 FG, 1-2 3Pt), two rebounds, and one steal in 15 minutes during Sunday's 119-109 win over the Hornets.
Johnson is expected to start Sunday's game against the Hornets in place of E'Twaun Moore (calf), Pels' studio host Daniel Sallerson reports.
Johnson will start Saturday against the Nuggets.