For the second game running, Natalie Stafford led Great Britain with 21 points and she also pulled down six rebounds.
"I thought we did a good job defensively. We improved our defensive switches and we got quite a few steals in the game leading to us getting some good lay-ups," Stafford said. "No doubt for us, this was an improvement and a good step forwards going to the Olympics."
Jo Leedham supported with 16 points, while Manchester-born forward Julie Page hit 13.
Despite a slow beginning from both sides, the pace of the game quickened, leading to GB taking a slender 24-22 lead at the end of the first quarter.
It was from the second period that Great Britain showed its class, going on a 19-3 burst in the final five minutes to lead 51-35 at the half.
Belgium were a beaten side from there, as GB pushed the lead to 20 mid-way through the third quarter and maintained their cushion to lead 74-54 going into the final ten minutes where they controlled the tempo to record an easy victory, leaving Maher a happy man.
"We're not getting too carried away with the win, we're not at that level to be doing that yet but in these last two games, our positive aggression has jumped to a new level which is great to see," he said.
Maher added: "We are now showing a new and improved mental toughness which is great and technically, we are still trying to get through things but we have a long way to go and time is on our side."
Jasmina Roseel led Belgium's scoring with 22 points.
GB will now head home to play two test matches against Canada next Saturday and Sunday afternoon in Edinburgh.
