The offer came through his father, Frank, who has a connection with Michigan recruiting coach Chris Partridge, who coached against Robertson last fall, when he was the head coach of Paramus (N.J.) Catholic.
"I played against him my junior year and we lost. And then I played against him my senior year and I won. So he knows how I play," Robertson said of Partridge. "He was recruiting me and was just talking with me a lot. My dad asked me if I wanted to go [to Michigan on a visit]. I said 'Yeah, of course.'"
Robertson, who had notable offers from West Point, Citadel and Sacred Heart, continued to explain his reason behind choosing Michigan.
"We went up there for a visit," Robertson said. "I love the place, it's crazy. It's great atmosphere. It's a great campus. It's great facilities that they got there. I just decided that would be the best fit for me and I would work hard and earn that scholarship."
Robertson says Partridge offered him as a preferred walk-on before his visit to Ann Arbor, however, he couldn't commit until he was accepted to the school. During his visit he would learn he would be accepted into Michigan's school of Kinesiology.
And then, of course, he had a chance to meet his future head coach -- Jim Harbaugh.
"He is a great guy, man," Robertson said of Harbaugh. "He's just very straight forward. He said 'You look like a good athlete. We're ready to have you.' I'm just ready to work for him.
"He told me: 'NFL is an option, it's not hard to get. You just got to work.'"
Next up for the 6-foot-5, 220-pounder is graduation and then preparing for his career at U-M.
"I got to finish school," Robertson said. "Once I graduate it's time start working hard. They want me up there June 26 I believe.
"I can't wait to be up there. It's going to be great."