The European indoor champion finished clear of rival Eilidh Child in a time of 54.36seconds to secure her place at the World Championships.
Shakes-Drayton controlled the race at the Alexander Stadium from the start, holding off a late surge from Child for a commanding victory.
And now she is ready to turn her attention to Moscow and the World Championships.
"I am pleased to retain my title," said the 24-year-old. "As much as I may have come here as the fastest I still wanted to come and perform well in front of the crowd.
"I would love to come home with a medal from Moscow but I will get to the final first and see what happens then."
Sainsbury’s British Championships is the second event in the Sainsbury’s Summer Series.
- Sports & Recreation
- Eilidh Child