It was his 12th Isle of Man TT title since making his debut in 1996 and his second consecutive victory in the class for electric bikes.
Anstey’s team-mate Guy Martin finished second, 48.417 seconds behind. Anstey said: “A win is a win and I’m made up with it. The bike was amazing.”
Martin, who will not compete is the Senior TT later on Friday, added: “It is the future in some way or other. I’ve got loads to learn but it was class.”
Daley Mathison completed the podium 48.41 seconds down on Martin for the University of Nottingham team.
Dean Harrison finished fourth, with Antonio Maeso fifth and James Cowton sixth.
Six of the eight machines that started completed the one-lap race.