Rafa Benitez welcomes key man back for Newcastle's visit to Villa
However, Vurnon Anita is expected to continue at right-back at Villa Park, having recovered from a minor problem.
Janmaat has been sidelined for almost a month with the groin and hand injuries he suffered at Southampton.
Advertisement
Hide AdAdvertisement
Hide AdBut he is ready to return to the field, though he will have to wear a cast to protect the hand he fractured punching a door at the St Mary's Stadium.
However, Anita, forced off late in last weekend's 1-0 win over Crystal Palace, is likely to get the nod against Villa.
Captain Fabricio Coloccini (calf) remains sidelined.
Asked about injuries, United manager Benitez said: "“Anita fit, Coloccini still out, Janmaat available."
Relegation-threatened Newcastle are 17th in the Premier League and a point above Sunderland, who have a game in hand.