Bolt is halfway through what may be the final chapter of a historic Olympic "triple-double" in the men's sprints, as he hopes to add the 200m gold to the 100m crown for the third consecutive Games.
The Jamaican won the 100m final in 9.81 seconds on Sunday night (Rio time), beating home Justin Gatlin (9.89) and Andre De Grasse (9.91) for the gold.
He is focused on a third straight victory in the 200m, which he also won in Beijing (2008) and London (2012), and moved a step closer when he strolled across the line to win heat nine in 20.28.
The 29-year-old shut down with 50 metres left in the race, preferring to peer over to his right more than once at Nigerian Ejowvokoghene Oduduru, who was second in 20.34.
"I've recovered from the 100m. I'm tired now, but happy to be through," Bolt said after his heat run.
"I'm looking forward to tomorrow (semi-finals)."
Gatlin and De Grasse moved through to the semi-finals without any trouble, clocking 20.42 and 20.09 in their heats respectively.
Australia's Alex Hartmann, making his Olympic debut, was fifth in his heat in 21.02 but did not qualify for the semi-finals.
Meanwhile, Christian Taylor of United States won back-to-back gold in the men's triple jump, leaping 17.86m to take the win.