Mussa, who may initially form part of John Ward's Development side, is a Belgium Under-18s international and has penned a deal until the end of the current season, with the club having an option to extend should they see fit.
Mussa, who has been training with Dean Keates' squad for the last month, came up through the ranks at Mechelen and has been capped at various youth levels for Belgium and arrives at the Banks’s Stadium after the Saddlers came to a compensation agreement with Mechelen for his services.
Walsall manager Dean Keates spoke to club journalists and welcomed Omar to the club, he said; "We have had a look at him over the last few weeks and he has really impressed us. He has been involved with the Under-18s for Belgium and is an attacking midfielder player but a bit different to what we have in the group at the moment.
"His technical ability is exceptional. He has got great feet, can pick a pass and strikes a great ball. He is a welcome addition to the squad going into the second half of the season."
Walsall manager Dean Keates spoke to club journalists and welcomed Omar to the club, he said; "We have had a look at him over the last few weeks and he has really impressed us. He has been involved with the Under-18s for Belgium and is an attacking midfielder player but a bit different to what we have in the group at the moment.
"His technical ability is exceptional. He has got great feet, can pick a pass and strikes a great ball. He is a welcome addition to the squad going into the second half of the season."