Some 350 people have so far signed up to take part in the popular event being held on Sunday at Sandwell Valley Country Park, in Salters Lane, West Bromwich.
Organisers say there is room for more to register at the starting line at 9am.
The run which is being held for the seventh time raises money for the Smile for Joel charity, set up by Suzy Evans and her surviving son Owen Richards, from Wednesbury.
They pioneered the organisation after her eldest son, Joel Richards, aged 19, her brother Adrian Evans, 49, and father Patrick Evans, 78, were all killed in the Tunisia beach gun attack in 2015. Owen, who was 16 at the time, survived.
The profits raised will be spent on supporting bereaved families affected by murder and manslaughter across England and Wales.
Ms Evans says: "We are really excited for this year's event. We've got 350 people registered. Registration has closed, but people can turn up and pay on the day as long as they come at 9am. We are expecting more foot fall and nice weather to boot.
"There are lots of trophies this year and everyone will get a special Run For Joel wrist band.
"The day will start with a warm-up session with a powder paint activity and we're advising those who want to take part in the colour jam to wear sunglasses to prevent it getting in their eyes.
"It's the seventh time we've held the run and we have been amazed at how many people have like it and how happy they are to come out to support Smile for Joel."
There will be a 5K race at 10am suitable for adults and experienced athletes, followed by a 3K race suitable for families at 11am.
Entry for the 5K costs £15 for all participants and the 3K costs £12 for adults and teens, children aged 12 and under £5 and free for infants aged under two. Bring cash to pay on the day.
For more details see Facebook or visit smileforjoel.com/event-details?event=runforjoel-2023