
The 25-year-old, who enjoyed a highly successful loan spell with the Pilgrims in 2005-2006, has signed a contract until the end of the season at The Jakemans Stadium.
After making 14 appearances for Harrogate this season, Ross left Wetherby Road last week and his linked up once again with former Boston and Notts County team-mates Jason Lee and Lee Canoville.
Ross marked his senior debut with the winning goal for Sheffield United against the Pilgrims in August 2005’s Carling Cup tie — before joining Boston on loan shortly afterwards.
He scored four times in 16 appearances during a three-month spell with the Pilgrims and was duly named Powerade player of the month in Coca-Cola League 2 during his stint in Lincolnshire.
Further loan spells with Bury, Notts County and Rotherham United followed — before Ross dropped into non-league football with Gainsborough Trinity and Alfreton Town.
The dynamic midfielder played a key role in the Alfreton side which claimed the Blue Square Bet North title last season.
Ross is eligible for Saturday’s FA Trophy clash against Workington.
Stay tuned to bufc.co.uk on Wednesday morning for an exclusive video interview with United's new signing.