Argentine champions Boca, participating in this fixture for a fifth time, failed to live with their opponents as Barca kicked on from where they left off in last season's double-winning campaign.
Malcom had his dream debut goal with 18 minutes on the clock, beating his man on the edge of the box and firing a low effort under Andrada, who could not react in time.
Barca took complete control of proceedings pretty much from that point on as midfield duo Coutinho and Arturo Vidal, as well as Messi, grew more and more into things.
The hosts deservedly doubled their tally before the interval through a trademark Messi clip over Andrada after the ball bounced into his path.
Boca's best chance of pulling one back arrived right at the end of the opening 45 minutes, but Edwin Cardona hit the post from a good position and Samuel Umtiti was well placed to block the follow-up on the line.
Ernesto Valverde made eight changes to his side at the break, giving the likes of Clement Lenglet and Arthur a chance to sample the Camp Nou atmosphere, but it was one of those who remained on the field who had the first chance of the second period.
The game was killed off a little over half an hour from the end courtesy of Rafinha's poked finish at the end of an impressive individual run.
BARCELONA (4-3-3): Ter Stegen (Cillessen 46'); Miranda (Dembele 65'), Umtiti (Vermaelen 46'), Pique (Lenglet 46'), Roberto (Semedo 46'); Coutinho (Puig 45'), Rakitic (Arthur 46'), Vidal (Rafinha 46'); Malcom (Suarez 65'), Munir (Busquets 65'), Messi (Alcacer 46')
BOCA JUNIORS (4-3-3): Andrada; Buffarini, Goltz, Izquierdoz, Olaza (Mas 77'); Nandez (Tevez 64'), Barrios (Almendra 64'), Reynoso (Perez 46'); Villa, Cardona (C.Pavon 46'), Abila (Zarate 46')