The B577 was a rural B-road in southern Leicestershire.
It started on the A5 at High Cross, the point where the Fosse Way crosses Watling Street, and headed east. It zigzagged through Claybrook Magna and Claybrook Parva and into Ullesthorpe, where it crossed the Rugby to Leicester railway line at a bridge that is still in existence even though the line closed in the 1960s.
The road then continued southeastwards via Bitteswell to Lutterworth. It entered town along Bitteswell Road and then ended on the B4111 (later A427) Coventry Road in the centre of town.
The B577 lasted until at least the 1990s but is now unclassified.