Last-minute signing Felix opened the scoring with the home side’s first attempt in the 11th minute, netting with a low strike inside the near post.
The Portuguese then set up Lewandowski inside the box to double their lead eight minutes later as the Poland striker became the third player to score 100 goals in European competition after Cristiano Ronaldo and Lionel Messi.
Winger Arbnor Muja had a chance to give the visitors a glimmer of hope just before half-time, but his low effort from the edge of the box was kept out by goalkeeper Marc Andre ter Stegen.
Xavi Hernandez’s Barca returned after the break determined to increase the advantage in their 28th Champions League group stage campaign, a competition record shared with Real Madrid.
They did not have to wait long as Gavi made it 4-0 by smashing the ball into the roof of the net before Felix added another goal with a header to complete the rout at Barca’s temporary home while Camp Nou is being redeveloped.
Barca’s dominance was reflected in 22 goal attempts compared to only three from Antwerp, who were playing in the Champions League after winning their domestic league title for the first time in more than 60 years last season.
It is the Belgian side’s fifth successive campaign in Europe and their second in the continent’s leading club competition after they featured in the European Cup in the 1957-58 season.