Aldred, 27, has made 23 appearances at Gigg Lane this season and told the Steelmen’s website that he was ‘really looking forward’ to getting started at Fir Park.
He said: “I’m really looking forward to getting my head down, working hard and being the best I can be.”
‘Well boss Stephen Robinson hailed the arrival of the experienced defender, adding: “We were clear from the start of the January window we were looking to increase our options in central defence.
“Tom ticks that box and arrives at the club with plenty of experience under his belt. We tried to get him in the summer, so we are delighted to finally have him at Motherwell.”
The former Blackpool centre back has first-hand experience of the Scottish top flight from a previous loan spell with Inverness Caledonian Thistle in 2011.
He started his career with Carlisle United before sealing a move to Watford in 2010. However, he struggled to hold down a regular starting berth and joined Accrington Stanley in January 2013.
A loan move to Blackpool in 2015 became permanent and Aldred spent three seasons with the Seasiders, captaining them to League Two play-off final success last season.
The 6ft 2in Aldred has also had loan spells at Workington, Stockport County, Torquay United and Barrow.