The France international has not played since the 2-1 win over Everton at the beginning of October, and he has only played for 135 minutes so far this season due to injury.
United trained without Jadon Sancho or Antony, but the return of Martial will come as a boost to manager Erik ten Hag.
The 'Red Devils' can top Europa League Group E and avoid a play-off game if they beat Sociedad by more than two goals on Thursday evening.
Real Sociedad train ahead of Man United test in Europa League
Real Sociedad trained at their base in Zubieta on Wednesday in preparation for a group-deciding Europa League clash with Manchester United.
'The White and Blues', who beat Man United 1-0 in their opening game of the group stage, head into Thursday's final match in Group E sitting three points clear of 'The Red Devils' at the top of the standings.
But a 2-0 win for the visitors at Estadio de Anoeta would see United leapfrog Sociedad into first place and avoid a play-off for a spot in the knockout stage of the competition.