The England Under-18 international made his first-team debut for the Pilgrims in a Carling Cup defeat to Millwall at the start of the season, in the process becoming the sixth-youngest player to ever play for the club at just 16 years and 288 days.
Lecointe has since gone on to make a total of 22 appearances, nine of which starts, and scored two goals - his first in a 3-2 win at Dagenham in October.
Argyle boss Carl Fletcher told the club's official website: "Matty has got good potential and he's a nice lad.
"He has been with the club since he was a young boy. He's a Plymouth lad and is exactly the sort of talent this club needs and has to bring on."