Chidi Uzomah Jr. was convicted last year of assaulting a security guard who was assigned to protect Seacrest at an Orange County event.
He pleaded no contest Tuesday to one count of felony stalking.
Uzomah, 25, was sent to prison to undergo a 90-day psychiatric evaluation. He's due back in Los Angeles Superior Court for sentencing on June 14.
Uzomah was arrested at the E! headquarters in the Miracle Mile area armed with a pocket knife on October 30, 2009, according to Los Angeles police Detective Rosibel Smith, who is assigned to the LAPD's threat management unit.
Detective Smith testified that Seacrest told her that he was "very intimidated by Mr. Uzomah's presence, by his size" after being informed that the defendant had shown up to see him at the E! building. Uzomah is 6 feet 4 inches tall and 200 pounds.
"His aggressive and violent efforts to come into physical contact with me are extremely frightening to me," Seacrest wrote in a declaration filed in November to obtain a restraining order against Uzomah. "They have jeopardized not only my personal safety, but also the safety and well-being of those around me."
Uzomah was previously arrested for attacking a security guard while trying to get close to Seacrest. He was sentenced to 15 days in jail and three years of probation after pleading guilty in the assault. He was also ordered to stay away from Seacrest.
"He was very much in fear of him," Smith testified, noting that Seacrest knew Uzomah had also been carrying a knife when arrested following his Sept. 15 encounter with the defendant after a charity event at Children's Hospital of Orange County.
According to the detective, Seacrest said he looked in his rear-view mirror and saw Uzomah involved in a physical confrontation with a security officer.
Seacrest said he was also informed that Uzomah came to the KIIS-FM studio in Burbank on Oct. 2 to look for him, Smith testified.
The detective noted that Uzomah's probation conditions for the Orange County run-in required him to stay 100 yards away from Seacrest and Children's Hospital of Orange County and not to own, use or possess any dangerous or deadly weapons.
In exchange for Uzomah's no-contest plea, prosecutors will drop two misdemeanor counts of disobeying a court order.
He faces up to two years in prison.