The former England batsman scored 2,934 runs in all cricket, including 1,817 first-class runs at an average of 75.70.
Trescothick, who will take over the Somerset captaincy next season, had already won the Most Valuable Player award, which was given automatically on a points tally secured by his runs but Thursday's honour was the result of a vote by his fellow professionals in the Professional Cricketer's Association.
Leicestershire's 19-year-old batsman James Taylor, who also topped the 1,000 runs mark, was named the young player of the year.
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