Lusi is a village () located in the Finnish municipality Heinola in the Päijät-Häme region, in the former Province of Southern Finland. It is where Finnish national road 5 meets Finnish national road 4.
In 2009 Lusi was nominated village of the year.
Lusi was first mentioned in 1470. It was originally a farm name, derived from a folk form of the Christian given name Ambrosius (Brusi > Blusi > Lusi).
Lusi was a part of Heinolan maalaiskunta until its consolidation with the town of Heinola in 1997.