The Class of ’92 graduate was driving carelessly through Burnley, Lancashire, when he failed to spot the rider.
Victim Andrew Fielden suffered a broken left leg, which needed metal rods inserted following an operation, and severe bruising.
Butt, 49, appeared at Blackburn Magistrates’ Court today where he admitted causing serious injury by careless driving.
The former England star was handed am intermim driving ban following the October 2022 crash.
He could face up to two years in jail or an unlimited fine when he is sentenced on a date to be set.
Butt was a instrumental part of Alex Ferguson’s youth team – rising through the ranks with David Beckham, Ryan Giggs and the Nevilles.
The midfielder began his professional career stepping in for Roy Keane as a sub before he landing a full-time spot when Paul Ince left in 1995.
Along with the rest of the Class of ’92, Butt helped Utd win countless trophies as the club became a dominant force.
This included the Champions League Final in 1999, where the Red Devils made history by winning the treble.
By the time he left in 2004, the footballer had helped Utd win six Premier League titles, three FA Cups and a Champions League trophy.
Butt later had spells at Newcastle and Birmingham City before moving into management in 2016 for Utd’s U23 team.
In 2014, he bought Salford City along with Ryan Giggs, Paul Scholes, and Gary and Phil Neville.