The former Rangers and Livingston goalkeeper spent the second half of last season on loan at Motherwell making 21 appearances – and was even touted in some quarters to be considered for Steve Clarke’s Scotland squad heading to Euro 2020.
He’ll now be back, permanently, after Alexander sealed a deal with the west London club and signed the 25-year-old on a three-year deal.
“It’s been a long process but the board have been great with their patience and backing as we worked to get this deal done,” he told his club website.
“We all saw Liam’s qualities first-hand last season. His ability, professionalism and drive will improve us again. Everyone is delighted to see him back in a Motherwell shirt.”
It’s the second Steelmen signing in the past week, following the signing of Scunthorpe striker Kevin van Veen.