On Tuesday night's episode of America's Got Talent, the country singer won over the crowd and judges after he performed his original song "Kiss Goodbye All Night."
Dubbing Milligan "the best performance of the night," Cowell told the 24-year-old how much he respected him for returning to compete after the success of his audition with his original song, "Sounds Like Something I'd Do", which hit number one on the iTunes country chart.
"I've got to say something, Drake. A lot of people after performing on the auditions and their song goes to number one, they would just walk and not compete," Cowell, 62, told Milligan. "The fact that happened, and you still come back to compete in this competition, you have my absolute respect because I was really concerned about that."
He added: "In my opinion, I think you are the real deal. You're a great songwriter. You have real charisma. I'm with Howie, based on tonight ... this is, in my opinion, the best performance of the night."
NBC Drake Milligan and Simon Cowell
Cowell even went as far as to post the clip from the episode where he sang Milligan's praises on his Instagram.
"It's quite amazing to get your song to number 1 during @agt and then come back and carry on the competition. You have my absolute respect @drakemilligan," he captioned the post.
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Following the live show, Milligan spoke with PEOPLE about performing another original song on the AGT stage — and the positive response he received from both the crowd and judges.
"We really wanted to go out there and raise the bar. That's something I want to keep on doing is hopefully go on and keep raising the bar," he said. "Going out there in front of that crowd was really, really special."
On what it was like for him to receive such praise from the judges, Milligan said, "It was amazing. I mean, to hear Simon say that [my performance] was the best of the night so far was just awesome."
Milligan also talked about how "life-changing" the support from fans and viewers have been since his audition.
"It's everything I've dreamed of as a songwriter and as a singer is to have people listening to my songs and coming to shows and singing along my songs," he said. "And AGT has done that for me. They really, really changed my life forever."
Moving forward, the contestant said feels "good" about his chances at winning, despite how the competition is "so so tough" this week.
"Avery [Dixon] just absolutely was amazing [to] close out the show. And there's everybody [who] was so so good," he told PEOPLE. "I'm hoping I did my best out there and I can go on because I just want to get back on the stage."
Fans will find out if Milligan is one of two viewer-voted contestants to move onto the season 17 finale when the AGT results show airs Wednesday at 8 p.m. ET on NBC.