Johnson made 10 of his 13 first-half shots and ended up with 29 for the game. The Nets, 16-22 overall, are 8-3 this season when Jackson scores at least 20 points.
He scored 10 straight Brooklyn points late in the first quarter and eight over the latter stages of the second period as the Nets took a 65-53 edge into halftime.
Brooklyn pushed its advantage to 25 points by the end of the third period and was up by as many as 33 with 9:07 to go.
Johnson ended up with 29 points on 11-of-15 shooting in leading the Nets to a 58.2 percent shooting game. He also made 6-of-8 3-point tries, helping Brooklyn to 59.3 percent shooting from beyond the arc.
Andray Blatche added 20 points and 14 rebounds while Paul Pierce scored 19 points for the Nets.
The game in London was part of the NBA's 201-314 Global Games series.