The 39-year-old - who was player-manager at Priestfield until November when he stepped down to return to just a playing role - will be with City until 3rd May.
The 5'7" veteran has been a regular for the Gills since joining them over 8 years ago, and in that time has been managed by current Tigers boss Peter Taylor, as well as playing alongside Junior Lewis, Roland Edge and first team coach Steve Butler.
He joins City to strengthen the midfield, which will be without the suspended Ian Ashbee and Michael Keane in forthcoming games.