Arsenal announced Martinelli as the winner, in a three-man shortlist which also had Granit Xhaka, on their official website on Wednesday.
Martinelli claimed 49 per cent of the votes cast, Xhaka in second place with 31 per cent and Saka in third placewith 20 per cent.
The 18-year-old was in fine form in January, firstly scoring in the 1-1 draw with Sheffield United at Emirates Stadium.
He ran 67 yards to score a sensational goal in our 2-2 draw with Chelsea at Stamford Bridge.
He then provided an assist for Saka against in the 2-1 win at Bournemouth in the fourth round of the Emirates FA Cup.
So far this season the teenager has already scored 10 goals in just 21 appearances, while also contributing three assists.