The 53-year-old won all four of his matches to retain the Men’s Over 50s title at Inverness Tennis and Squash Club.
Top seed Robertson defeated sixth seeded Russell Hunter in the final, 11-3, 11-8, 11-4.
He said: “The final went exactly to plan, I was pretty consistent throughout and I am very happy.
“The last time we played earlier in the season Russell fought back from 2-0 down and that was on my mind in the third game.
“I made sure I didn’t relax and let him back in. I found my length early and managed to pin back a dangerous opponent.
“I didn’t give many cheap points to Russell which was a theme over the weekend for me.
“I have played twice a day at times recently which helps in terms of your overall fitness for events like this.
“That also helps you fight through tricky moments.”