The triple European champion clocked 10.96 seconds at the Alexander Stadium on Saturday.
It came after confusion when the trackside clock stopped at 11.03 seconds before the official time was finalised. Asha Philip came second in 11.29secs while Daryll Neita finished third.
The event doubles as the trials for the World Championships in Qatar next month, with the British squad announced in early September.
But Asher-Smith appeared frustrated after running over 11 seconds in the semi final, 11.03s, for the first time this year.
In the men’s 100m Zharnel Hughes surprisingly finished third behind winner Ojie Edoburun and Adam Gemili, who booked their spots in Great Britain’s World Championships team.
Edoburun took the title in a photo finish in 10.18s.
European 100m champion Hughes does not now automatically qualify for Doha, although he already had the selection time, yet is all but certain to get the selectors’ discretionary place.
It ends Reece Prescod’s hopes of reaching Doha with Edoburun and Gemili qualifying. Prescod missed the weekend as he battles a hamstring injury.
Heptathlon hopeful Katarina Johnson-Thompson ran 13.57 seconds to come fourth in the 100m hurdles and threw 12.60 metres to finish eighth in the shot put
She is fine-tuning her events ahead of Doha and competes in the javelin on Sunday having come second in the long jump, behind heptathlon rival Nafi Thiam, at last week’s Diamond League meet in Birmingham.
She said: “I’m disappointed with the hurdles, but obviously the wind didn’t help. I think I just needed those two races under my belt.”
Cindy Ofili won the 100m hurdles while Sophie McKinna was victorious in the shot put to bank her spot in the GB squad.
Rosie Clarke, who already had the qualifying standard, took the 3000m steeplechase.
Andrew Butchard won the 5000m to book his place on the plane for Doha in a time of 13 minutes 54.27 seconds.
He said: “A confident mindset in the past few races I’ve had has definitely helped me. “I’ve had good races all year this year but I’ll be trying to get even fitter and hopefully will go into Doha even more confident. Medals are always up for grabs.”