The Southfield (Mich.) defensive end faxed in his signed letter of intent with his mother's signature after 11 p.m. Tuesday.
"I talked to Malik this morning, he's thrilled, ecstatic about everything," coach Mark Dantonio said.
It was a long process since signing day, as McDowell's parents had to be sold fully on Michigan State before deciding to jump on board with their son's decision.
Dantonio said it took addressing their "legitimate concerns" and that he would be a student first, get a degree and lastly, will be a good football player in East Lansing.
"They didn't want it to be impulsive," he said. "I've always said many, many times, when you're unsure of some things you try and slow the game down.
"I think that's what the family did, they tried to slow it down, make sure this is what he wanted and it tested them at every turn in this area because this is a big, big decision."
He credited McDowell's parents for keeping the communication open between the two sides in the past months.
"What we had to do is we had to be able to work through the process until everybody felt comfortable with this," he said. "I thought it was very important that everybody be on the same page when we made this decision, or they made the decision, so what I tried to do on my end is sort of just be still."
McDowell had announced his commitment to Michigan State at Southfield High School the morning of signing day, but the letter was not faxed in that afternoon. It became clear that the letter was not headed to East Lansing that day or the following days.
Dantonio said the goal was to address the concerns quickly and get things resolved, but it was evident it would take more time.
"You always try to be patient and basically, as I said earlier, try to not rock the boat too much," he said. "Be still and let the process take place. I think this is the best place for Malik McDowell. I sincerely think that, but I wanted him to find the best place for him, too.
"I didn't want it to be all about us. In the end, I think that's what happened."
McDowell is expected to contribute right away in East Lansing and can play either defensive end or defensive tackle, as Dantonio said he has "unique ability."
"I think Malik will be on the field for us," Dantonio said. "I just think he is too big, strong, fast. …
I think he's going to be on the field, based on what I've seen from him in camps and his raw, physical ability."