Nicholson has spent the first half of this season on loan at Nuneaton Town, scoring 12 and assisting 7 in 27 appearances.
He made his Football League debut with the Posh in 2016 but spent the following season on loan at Nuneaton where he enjoyed a successful loan spell, prompting a second spell this season.
He started his career at Cambridge City, before moving to Eynesbury Rovers and then Histon. His performances at Histon saw him move to Peterborough in December 2015.
Welcome to Barnet FC, Jordan!