Four days after winning the 100 metres, Lyles, twice world 200m champion, ran 19.76 seconds to record the fastest time in Thursday's semi-finals.
Lyles' heat was delayed by 30 minutes after the golf cart transporting him and the other runners from the warmup track to the stadium crashed into another cart.
Heats two and three were run before the first heat as Jamaican Andrew Hudson received medical treatment for glass in his eye.
Hudson was fifth in the heat and did not advance.
"I feel like it all happened in slow motion," Hudson said.
"Unfortunately, I was sitting on the side where another buggy crashed into us, I was directly impacted. They got most of the glass out. My eye is pretty blurry right now."
"It is my first world championships so it's going to be memorable... Maybe I'd better walk next time."
American Kenny Bednarek, the Olympic silver medallist, ran 19.96 for the second fastest time, edging Letsile Tebogo of Botswana, the 100m silver medallist who crossed in 19.97. Bednarek glanced across at Tebogo just before the finish line.
"I wasn't playing mind games (with Bednarek) at the end there," Tebogo said.
"He looked at me and in my mind, I was like, 'Why is he looking at me? Just keep going, keep going'."
Lyles is seeking to become the first man to win the sprint double since Usain Bolt in 2015.
American Erriyon Knighton qualified fourth and Britain's 100 metres bronze medallist Zharnel Hughes, who beat John Regis's 30-year-old national record in the 200 this season, was fifth.
Olympic champion Andre De Grasse, who has been hampered by a foot injury this season, sneaked in as one of the two fastest losers with a time of 20.10.
"That was tough," De Grasse said. "I'm missing that 100 speed, of course, and they got away from me on the turn, which doesn't usually happen. But I live to fight another day, I guess."
His teammate Aaron Brown was disqualified for stepping on the lane line.
