It is set to be the first big event to take place in the town as restrictions continue to be lifted following the most recent lockdown.
Organisers have put in place rigorous procedures to make sure the marathon can pass of safely.
A spokesperson for Boston Marathon said: “We are absolutely delighted our May event is going ahead. We are amongst the first marathons to go ahead this year consequently we are fully booked and had to close registration early.”
There are 1,000 runners in the full marathon, 800 in the half marathon, and 200 taking part in the 5k fun run.
The main race is due to start at around 8am, with the half marathon at 9am and the fun run at 9.30am.
Runners will be assembling in Central Park, where there is plenty of space for social distancing, before going to the starting area in the Market Place in smaller groups for a staggered start.
Organisers are keen for people to turn out on the route and cheer the runners on, but have asked people not to gather in the Market Place.
The spokesperson said the fact that the race filled up so quickly “goes to show just how excited our runners are too. Their training has been off and on for probably 2 years now and finally they are ready to run.
“Sport and physical activity are vital to the nation’s mental and physical health, now more than ever as we recover from the pandemic.
“Organised outdoor sport can take place with any number of participants, as long as undertaken in line with published COVID-secure guidance. We have taken every measure to mitigate the possible spread of Covid-19 by introducing new rules such as a large assembly area in the park with staggered arrival times and a wave start of 200 runners setting off every 10 minutes.
“We have been and will be working hard to make it safe and enjoyable for everyone involved.”
The route will see runners go from Market Place, to Main Ridge, onto Eastwood Road, Freiston,Butterwick, and Wrangle before turning back back to Freiston Shore, heading to Fishtoft and finishing at Boston College.
A number of roads will be closed around the route. Click here for full details.