Having lifted the Supercopa de Espana thanks to a slender 2-1 win over Sevilla on Monday (AEST), Barca again looked in good shape ahead of their title defence in LaLiga, which begins on Sunday against Deportivo Alaves, sweeping a feisty Boca aside with minimal fuss.
Barca gradually found its stride and went close for the first time in the 16th minute – Philippe Coutinho tricking his way past one opponent before forcing Esteban Andrada into flying save with a stinging effort.
Andrada made a mess of things shortly after, however, allowing Malcom's low drive to squirm under him after the Brazilian had squeezed a shot past Boca right-back Julio Buffarini.
The host deservedly doubled its lead six minutes before the break – Messi delicately chipping a fine finish over Andrada after his attempted pass to Coutinho came back off Buffarini and fell perfectly into his path.
But the club was fortunate to not concede on the stroke of half-time when Sebastian Villa broke into the area and fired against the left-hand post.
Barca was a little less fluid after eight half-time changes, but Malcom did at least test Andrada from long range in the 55th minute following a clever bit of play by Riqui Puig.
It eventually added a third 23 minutes from time – Rafinha playing a one-two with Luis Suarez, before flicking the ball over Andrada and knocking in from close range.
Paco Alcacer had a late goal disallowed for offside, but Barca eased to victory nevertheless.