The switch, which Toro Rosso first alluded to in August, means Verstappen will drive in an official Grand Prix session just three days after his 17th birthday.
"To already be participating in a practice session is of course a dream come true," said Verstappen, who recently completed a 400-kilometre test in a two-year-old Toro Rosso and has now obtained the mandatory FIA Super Licence.
"It is good preparation for next year, even if it's not something I could have imagined a few months ago."
Despite the likely interest in his first run in Toro Rosso's STR9, Verstappen pledged to ease himself into the 90-minute Suzuka session, saying his focus would be on gaining experience rather than instantly trying to impress the team.
"I am not going there to break any records, I just want to gain experience," he said. "I have actually been to Suzuka before, to take part in a go-kart race on the track that is located next to the main circuit's back straight. My dad has raced at Suzuka many times and he told me it's not an easy track to start on.
"For me it will be a very valuable experience, spending some time in the car and also getting used to working with everyone in the team, to prepare myself for next year. I have spent one day driving this track on the simulator, which helps a bit, but it's no substitute for driving it for real.
"My first impression is that it's not an easy track and for example it looks hard to get the combination right in the first esses. I have one and a half hours to drive there and I'm looking forward to doing a good job, for myself and for the team."
Verstappen's FP1 drive completes a whirlwind two months for the Dutchman, who joined Red Bull's junior programme in August, and had his 2015 Toro Rosso drive confirmed just six days later. He is set to become the youngest race driver in F1 history at next year's season-opener in Australia.
Spain’s Jaime Alguersuari currently holds the record for the youngest driver to start a Grand Prix, having made his debut for Toro Rosso - in Hungary 2009 - at the age of 19 years and 125 days.