In 1978, Horton graduated early from Mount Tahoma High School in Tacoma, Washington, where he was a prep All-American.

[1] Horton accepted a football scholarship from the University of Washington, where he played as a cornerback and special teams from 1980 to 1982 after a redshirt year.

He finished as a three-year starter with 10 career interceptions, 22 passes defensed, including 14 (school record) in 1981 and played in two Rose Bowls.

[4] The next year, Horton was named the regular starter at right cornerback after the retirement of Ken Riley, posting 66 tackles and 3 interceptions, including one returned for a touchdown.

In 1986, he was passed on the depth chart by rookie Lewis Billups and was moved to the nickel back role, making 55 tackles and one interception as the Bengals barely missed the playoffs despite finishing 10-6.

In Super Bowl XXIII, after being up 13–6 over the San Francisco 49ers at the beginning of the fourth quarter, driving from the Bengals 10-yard line, quarterback Joe Montana threw a pass towards Billups that he dropped in the end zone.

Towards the game's conclusion, Montana threw a 10-yard touchdown pass to John Taylor who was being covered by Horton, for a 20–16 lead with 34 seconds left and the eventual championship.

In 1990, he sprained his left knee in the fourth game against the New York Giants, that forced him to miss one contest and slowed him the rest of the season.

[11] On January 17, 2013, Horton was passed over for the promotion in favor of his former fellow Pittsburgh assistant Bruce Arians, leading to his prompt departure from Arizona.

[16] In 2022, Horton joined a class-action racial discrimination lawsuit filed by former Miami Dolphins head coach Brian Flores.