Craig Halkett penned a three-year deal with Hearts in the summer of 2019.
The former Livingston captain moved under freedom of contract.
Centre-half Craig was a near ever present for Livi last season, making 36 appearances in all competitions and scoring five goals, including one against Hearts back in December.
At the other end of the pitch, he was part of an impressive defence that has kept 15 clean sheets last campaign.
The 23-year-old came through the youth system at Rangers and, after loan spells at Clyde and Berwick Rangers, joined Livingston in 2016.
He was part of the successful side that won back-to-back promotions, winning the League One title in 2016/17 before skippering Livi to play-off success last season, booking their spot in this year’s Ladbrokes Premiership in the process.
Capped at Scotland U19 level, Craig made 144 appearances for Livingston, scoring 15 goals in the process.
It only took Craig seven minutes to score the first goal of his Hearts' career after he netted early into his debut against Cowdenbeath during the Betfred Cup.