The 25-year-old spent the second half of the 2019/20 season on loan at the Stadio Carlo Castellani, scoring once in 17 appearances before returning to parent club Hellas Verona.
Henderson could be involved in Empoli’s Coppa Italia clash with Vicenza this Sunday, while his first league involvement could be in the home meeting with Lazio on August 21.
The Livingston-born midfielder won a clutch of honours in Scotland and Norway including helping Hibs to their historic Scottish Cup win in 2016, before first moving to Italy when he joined Bari in 2018.
He played 18 times and scored twice but the Serie B side was declared bankrupt at the end of the season and he joined Hellas Verona that summer.
Despite helping Verona win promotion to Serie A via the play-offs, Henderson joined Lecce on a four-year deal in September 2020.
He scored four goals in 42 games as I Giallorossi finished fourth in Serie B, registering seven assists – joint-fourth highest in the division – but will now get another shot at Serie A after his brief spell in the Italian top flight with Verona after Lecce failed to win promotin through the play-offs, losing 2-1 on aggregate to eventual winners Venezia in the semi-finals.
Empoli finished top of Serie B last season, winning promotion and enjoying a 28-game unbeaten spell.
They won 19 of their 38 games, drawing 16 and losing just three and finishing four points ahead of runners-up Salernitana.