Polworth, 21, came through the youth ranks at Inverness and made his Scotland Under-21 debut this year.
This season, Polworth has scored five times for John Hughes' side, including a double against Hamilton Academical in December.
He has made over 70 appearances for the Scottish Premiership club.
Inverness Caledonian Thistle have agreed a three-year contract extension with midfielder Liam Polworth, tying him to the club until 2019.