Triple Olympic champion Bolt, who infamously false-started and was disqualified from the final two years ago in Daegu, took no chances on his first appearance in the Luzhniki stadium with a win in 10.07.
"I'm happy with my run. I took it easy as it was the first round. I just wanted to get my reaction and start right," he said.
Bolt is hot favourite for the title in the absence of injured 2011 winner Yohan Blake and 2007 champion Tyson Gay who announced last month he had failed a dope test.
The decathlon is among five other golds to be decided on the second day of the championships and world record holder Ashton Eaton holds a nine-point lead over US team mate Gunnar Nixon with the 110m hurdles, discus, pole vault, javelin and 1,500m (1635) to go.
Any hope of an American sweep of the podium went when defending world champion Trey Hardee no-heighted in the high jump in Saturday's fourth event.
Ethiopia's Olympic champion Tirunesh Dibaba is unbeaten over 10,000m and favourite to win the women's final, a title she earned in 2005 and 2007.
Dibaba was the first women to win the distance double when she also took gold over 5,000 in Helsinki in 2005 but although the 27-year-old has been entered into the shorter race here. Ethiopian media reports suggest she will run only the one event.
Another athlete who has dominated her event, Sandra Perkovic, will attempt to win a first discus world gold. The 23-year-old Croatian has the top four throws in the world this year with a best of 68.96 metres.
"I've never won a world title - I was too young in 2009 (finished ninth) but now is perfect," she told Reuters.
Cuba's Yarelys Barrios leads the rest of the contenders and is aiming to become the first woman to win four successive World Championship medals in the event after silvers in 2007 and 2009 and bronze in 2011.
World and Olympic long jump champion Britney Reese had a scare, scraping into Sunday's final in 12th and last place on countback with 6.57 metres as Shara Proctor led the qualifiers with 6.85 despite taking off way behind the board.
The first medal of the day comes in the men's 20-km walk which includes Olympic champion Olympic champion Chen Ding, although the Chinese has been plagued by injury and has not finished a race winning gold in London.
Key times on day two (UK times)
16:00 - Women's long jump final
16:05 - Men's 100m semi-finals
16:35 - Men's 800m semi-finals
17:05 - Women's 400m semi-finals
17:15 - Men's discus throw final
18:05 - Women's 10,000m final
18:50 - Men's 100m final