She beat last year’s winner Jessica Warner-Judd by one minute 19 seconds, finishing in a time of 1hr 10mins 54secs.
It was more than three minutes outside her best time for the course and well outside her British record for the distance of 1:05:43.
But McColgan added: “I came into this race in a different place from previous years, coming back into training for the last four weeks, so fitness was always going to be my biggest concern.
“I had fear over the broken toe, [so] I eased into it because of nerves and could really attack in the second half.”
Britain’s Jack Rowe missed out on a record fourth consecutive victory in the men’s race, finishing in second place, 14 seconds behind Birchfield Harriers’ Kadar Omar Abdullahi, who won in a time of 1:01:51.
Britain’s David Weir defended his title in the men’s wheelchair event, winning the race for the fifth time in its nine-year history in a new record time.
The 47-year-old, who retired from Paralympic competition in 2024, knocked 45 seconds off his own record for the course, which he set last year, winning in 46:13.
Eden Rainbow Cooper won the women’s event in 52:47 to defend her title.