Crews from Wisbech found migrants living in poor conditions at the side of the A47 were often involved in accidents with vehicles.
The fire service decided to give out free luminous jackets to keep people "visible and safer" in the dark.
The BBC reported on conditions in the makeshift roadside camps in 2014.
Reporters found one squatter had died while crossing the busy road to get to the camp.
"We spend a great deal of time out and about in our communities identifying and supporting the most vulnerable people and this is no different," Wisbech station commander Phil Pilbeam said.
"After identifying the trend in the incidents we were responding to, we discussed and came up with the idea of providing hi visibility jackets for free to those who'd benefit from them."
The firefighters worked with a local group, the Rosmini Centre in Wisbech, "for support in how to engage the community".
"Hopefully, this initiative will allow us to work more with the variety of communities in Wisbech and improve access to them to share safety messages and important information in the future," Mr Pilbeam added.
Firefighters have given out high-visibility jackets to migrants in a bid to cut the number of crashes on a busy road in the Fens in Cambridgeshire.