A summer arrival from the Northern Irish club Glenavon, the versatile midfielder moves to Almondvale for the rest of the season after making four Hearts appearances so far.
Burns signed a three-year contract with the Edinburgh club in June and, at 18, is viewed as a prospect for the future by the Tynecastle hierarchy.
The move to Livingston is intended to let him continue developing by playing Scottish Premiership football week in and week out.
He had found himself on the periphery of the Hearts first-team recently but is expected to feature regularly under new Livingston manager Gary Holt. He will still be eligible to play reserve football for his parent club.