Williams has a two-year deal with the team, starting in 2019, but is currently riding with his future team as a stagiaire.
This season, riding for the Dutch SEG Racing Academy team, the 22-year-old from Newport, Wales, won two stages and the overall classification at the four-day Ronde de l'Isard in the French Pyrenees in May, and then went on to take a stage win at the under-23 Giro d'Italia in June.
Prior to SEG, in 2016, Williams rode for the John-Herety-managed JLT Condor team, which this week announced that it would fold after 12 years on the British scene.
Williams admitted to being a little nervous ahead of his first race with Bahrain-Merida, but was happy to see some familiar faces at the start of the Giro della Toscana, including Mark Donovan and Ethan Hayter – both currently riding as stagiaires for Team Sky. Hayter, like Williams, was part of the Great Britain team that rode the Tour of Britain earlier this month.
"To see us now in different pro kit is something strange," Williams said. "But it's great to see so many young British riders at the highest level.
"Although I've raced at this level so many times, when you pull on a jersey like this, it seems different. The last few days have been nerve-racking and daunting, but I'm sure it'll be like any other race," he told Cyclingnews at the start.
Williams was a non-finisher at Toscana, along with some 50 other riders, but after racing the Coppa Sabatini in Peccioli, Italy, with Bahrain-Merida on Thursday, he'll head to Innsbruck, Austria, as part of the British team for the world championships, where he'll take part in the under-23 road race on September 28.
"I'm hoping to come good for the Worlds," he said. "I had a bad patch through the Tour de l'Avenir and the Tour Alsace but hopefully, having done the Tour of Britain, I'll feel a bit better, and form will come back."
Looking ahead to 2019, Williams hopes to be able to use his first year with Bahrain-Merida to settle in and find out exactly where his strengths are likely to lie at the highest level.
"I hope to just find my feet at this level and improve gradually, and gain as much experience as possible in the first year," he said.
"Then I hope to see where my potential lies – whether it's in the high mountains or in one-week stage races, or at the Classics in the Ardennes. I really have to see where my talents and opportunities take me.
"There was really good communication with the team and they offered me a development path that was perfect for me, and which will help me to learn and improve," he continued, explaining his choice to sign with the team.
"That's what brought me in, along with riding with some of the best names in the sport. I couldn't turn it down."
Thanks to his slight build and aggressive racing style, Williams has often been compared to UAE Team Emirates' Dan Martin.
"I've always been compared to him, and that's great because I've always been an aggressive rider and liked to take the race on. I hope to keep continuing on that path with the help of all the people at Bahrain-Merida, who have so much experience at WorldTour level."
Williams agreed that there was now definitely more expectation from back home in Wales after Geraint Thomas won this year's Tour de France.
"But you always put pressure on yourself, too," he said. "Now I want to prove everyone right that I can ride at this level. I've done it at under-23 level, but I've got a clean slate now as I step up to WorldTour level."