The Argentine has been lethal from dead-ball situations in 2018, scoring six in all competitions since the start of the calendar year.
Leganes goalkeeper Pichu Cuellar became the latest goalkeeper to feel his wrath on Saturday, as Messi opened the scoring at Camp Nou with a stunning effort that gave him no chance.
It was his sixth in this year's Liga campaign alone, bringing him level with another Blaugrana idol.
Ronaldinho had been the last man to score six free kicks in a single season, a feat he achieved back in 2006-07 alongside the then-teenage Argentine.
Since the Brazilian left, Messi has assumed his mantle both as No. 10 and as Barca's set-piece expert.
6 - Lionel Messi is the first player to score six direct free-kick goals in a single La Liga season since Ronaldinho Gaucho in 2006/07 (6). Brilliance. pic.twitter.com/MWkEfcSpJf— OptaJose (@OptaJose) 7 de abril de 2018
Leo added another goal before half time to take his personal Liga tally to 28, eight clear of nearest Pichichi rivals Luis Suarez and Cristiano Ronaldo.