Marc McNulty has left Livingston to join English League One club Sheffield United on a three-year deal.
The Edinburgh-born striker was still under contract at Almondvale and his transfer will secure Livingston a six-figure sum, although the exact fee is undisclosed.
Nigel Clough, the Sheffield United manager, signed midfielder Stefan Scougall from the West Lothian club in January and has returned north to pluck their top scorer this time.
McNulty moves south after 19 goals in 39 appearances last season, and 45 goals in 88 starts for Livingston overall.
Livingston have sold their three most prominent young players since the turn of the year after teenage defender Coll Donaldson joined Queens Park Rangers in January. They have, however, received transfer fees for all three.
Manager John McGlynn must now identify a new striker for next season after Andy Barrowman was released at the end of the season.