The 31-year-old goalkeeper left Kilmarnock by mutual consent in early August to pursue first team football elsewhere after the Ayrshire club signed Jamie MacDonald from Falkirk.
It meant Samson found himself without a club a matter of months after being called into Gordon Strachan’s Scotland squad as a replacement for the games against Qatar and the Republic of Ireland in June.
Samson told Motherwell’s club website: “I am absolutely delighted to be here; I’ve spoken with the manager on a few occasions since leaving Kilmarnock and it was only last night we came to an agreement.
“I think this is a club going in the right direction. The team performed so well in the play-offs and this season they’re ready to kick on and do well. I believe the manager has added well and there is competition for every spot.”
This includes the goalkeeper’s jersey with Samson ready to battle Connor Ripley and Dan Twardzik to be first pick.
“Connor Ripley has been playing excellent since coming to the club and Dan Twardzik is here too,” acknowledged Samson. “I’ve got to work hard to impress the manager and try and get into the team.
“I know Connor has the jersey at the moment, I know Dan is pushing hard as well; so it is up to me to train hard and try and force my way in.”
Samson, who has made over 200 league appearances with clubs such as Ross County, Dundee, St Mirren and Killie, could make his debut on Saturday when Motherwell visit Hamilton at New Douglas Park.