The Barcelona captained scored 36 league goals this season, outshining Karim Benzema and Luis Suarez with 21 goals.
It is the third time in a row Messi has received the award and sees him equal the record for most wins that was set by legend Telmo Zarra 66 years ago.
He is also the top assister in La Liga, providing 13 assists throughout the season and is on course to win the European Golden Shoe for the third consecutive year and sixth in his career. He has scored four goals more than nearest challenger Kylian Mbappe who has one match outstanding.
With a tally of 50 in 49 games in all competitions, this is the fifth season in which Messi has reached at least half a century of goals.