Three years after a positive marijuana test saw her kicked off the US team for the Tokyo Olympics, Richardson captured the women's 100 final in 10.71sec with Melissa Jefferson second in 10.80 and Twanisha Terry third in 10.89.
Richardson surged to the lead in the middle of the race and crossed the finish line in this year's world-best time with a wind of 0.8m/sec at Hayward Field in Eugene, Oregon.
"I feel honored," Richardson said. "I feel every chapter I've been through in my life designed and prepared me for this moment.
"I cannot wait to go to Paris and represent."
Reigning men's 100m world champion Noah Lyles began his quest for Olympic gold in the event by leading all semi-final qualifiers from men's preliminary heats in 9.92.
Richardson hopes to capture Olympic gold in the 100 final at the Stade de France on August 3.
Not since Gail Devers in 1996 has an American woman been crowned an Olympic 100m champion.
The 24-year-old Texan won her preliminary heat on Friday in 10.88, leading all qualifiers despite a slight stumble at the start, and won her Saturday semi-final in 10.86, the best time of any finalist despite a slow start.
She was behind again at the start but quickly made up the time and charged to victory.
"Definitely didn't have the best start, but had a better start than my other rounds," Richardson said.
Three years ago, Richardson appeared set for the pandemic-delayed Tokyo Olympics after winning at the US trials in 10.86.
But dreams of Olympic gold were shattered when it was revealed she had tested positive for marijuana, resulting in a one-month suspension that banned her from Tokyo.
Plans to revive her career at the 2022 World Championships failed when she bombed out of the US trials.
Richardson, however, roared back into form in 2023 with a thrilling 100m triumph at the World Championships in Budapest, taking the crown in a championship record of 10.65sec.
This year, Richardson won her only prior 100 at May's Prefontaine Classic in Eugene in 10.83.
Lyles cruised to victory in the first of five 100m men's heats with Christian Coleman, the 2019 100m world champion, second in 9.99.
It's a redemption run for Lyles, who failed to qualify for the 100m final at the Tokyo Olympics and settled for bronze in a 200m final where he was a favorite.
"I felt like I just had blown a huge opportunity," Lyles said. "The more I look back at it, the more I'm like, 'Wow, if I never had that moment happen, I would have never produced what I've done up to now.'"
Lyles knows the pressure is high for success in France even after his world titles in the 100m, 200m and 4x100m relay last year.
"I know for people to take notice of me, an Olympic gold medal is needed," Lyles said.
Top five finishers in each of five heats plus the next two fastest runners reached the semi-finals, where Sunday's finalists will be decided.
Lyles ended any suspense, winning by .08 of a second over Kenny Bednarek in the opening heat with a 0.2m/sec tailwind. He was never going to threaten his season best of 9.85 or his personal best of 9.83.
"I had to make sure that my first 10 steps were powerful and open and after that I stood up," Lyles said.
"I knew I had the race in me. I knew I had it clear by 60 meters, which is why I ran more 60s this indoor season. And from there I just shut it down."
Crouser wins shot put
In the men's shot put, two-time reigning Olympic champion Ryan Crouser won the chance to defend his crown with an effort of 22.84m.
"Surprised myself a little bit," Crouser. "That's a good sign."
Joe Kovacs, the Rio and Tokyo Olympic runner-up to Crouser, was second at 22.43 to book his Paris trip as well.
Crouser, also the two-time reigning world champion, set the world record of 23.56m last year but has been nagged by injuries this year.
Other US trials wins went to Heath Baldwin in the decathlon and Jasmine Moore in the women's triple jump.
