The French top-flight's leading scorer took his tally to 15 with a goal in either half as Lyon made it three wins on the bounce, while sending Caen to the foot of the table on goal difference.
His seventh-minute penalty handed the hosts an excellent start at the Stade de Gerland on Friday against a Caen side who have not won in the league since October.
Things got worse for the visitors 12 minutes into the second half when Lacazette pounced at a corner to fire home, with Yassine Benzia completing the scoring.
Caen handed the advantage to Lyon early on when Jean-Jacques Pierre fouled Nabil Fekir in the box and Lacazette kept his cool from the spot.
Having spurned chances to double their advantage in the first half, Lyon got to work quickly after the break.
Fekir's corner was flicked to the back post by Samuel Umtiti and Lacazette was on hand to control and smash in from a tight angle.
Benzia added the gloss with a pinpoint first-time finish in the 62nd minute and there was still time for Remy Vercoutre to save Fekir's late penalty.
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