The former Chelsea FC trainee, who was a complete unknown at the start of this year, had been planning for next month's World Junior Championships in Barcelona.
But the Dartford teenager finished in 10.08secs at a meeting in Germany. It made him the second fastest European this year after France's Christophe Lemaitre.
Now he has decided to compete in both the World Juniors and the Olympics.
"I've got two weeks until the World Juniors so I'm just going to get my head down and train hard for that," he said. "That was my aim for this year until I ran 10.08secs and the Olympics became a possibility.
"After that it's all focused on the Olympics."
Gemili only made the full-time switch to athletics in January, having previously been on the books of Dagenham & Redbridge as well as Chelsea.
Having already attained the 'A' standard, the Blackheath and Bromley Harrier finished runner-up to Dwain Chambers in Birmingham to seal his Olympic spot.
He admitted that the scale of his achievement had only just hit home
"It took a while to sink in," he said. "The night after I ran I didn't get to sleep until three in the morning. I just couldn't believe it. It was a new feeling for me.
Chambers thunders to 100 metre victory
"People train their whole lives to do it. I'm lucky that I've come into athletics at the right time and I've qualified.
"I'm an 18-year-old and I've qualified for the Olympic Games, so to be picked at this age in front of all the sprinters in the whole country feels amazing."
Chambers, 34, is expected to get one of the 100m Olympic places
despite not achieving the 'A' standard this year.
His time at the trials of 10.25secs was seven hundredths of a second outside the required level. However, he ran 'A' standard times last summer - and selectors can take those into account.
Team GB, which will announce the athletics team next week, can take three 100m sprinters. James Dasaolu, the only other man with the qualifying mark of 10.18secs, held off Simeon Williamson to take third at the trials and is favourite for that final discretionary spot.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.