Cross Street Law Centre was formerly known as Thamesmead Community Law Centre.  It was set up by Plumstead Law Centre as an outreach session for Thamesmead in 1999, offering a drop in session at the Family Service Unit in Thamesmead.  As the local community became aware of the service offered by the law centre, demand increased, and staff moved into offices at St Pauls Church in Thamesmead in 2000 and ran drop in sessions from there. Additional funding was secured to employ additional workers, and 4 staff (2 full time, 2 part time) moved into Gallions in Thamesmead in 2002.

The staff were a collective and set up an independent Steering Committee in April 2006. It was decided that Thamesmead Community Law Centre (tmlc) should become independent, and it was registered as a Company (no 5932443), and a Charity (no 116273) on 12th September 2006.  It became independent on 1st April 2007. The Board discussed setting up a hierarchy with the staff, and the collective ceased in May 2007. An interim Manager was appointed until the Board appointed a Chief Executive Officer.

The premises at Gallions became unsuitable for Health and Safety reasons, so in 2007 the Law Centre moved to premises in Erith, an area of high deprivation.

TMLC was originally set up to cover the areas of Thamesmead, SE2, SE28 and the London Borough of Bexley.  On 15th July 2008, it changed its name to Cross Street Law Centre, and the area of benefit became South East England.