Thomas said the Giro is a “big target this year” and he will be “going to go all in for that”.
His race ended in agonising fashion last year as Roglic won the penultimate stage and after 80 hours of racing, beat Thomas by just 15 seconds.
“After the way it ended, I’d just like to go back and just get stuck into it,” Thomas said.
“Obviously Pog is riding and there will be a load of other good GC [general classification] guys. It’s a big challenge and I’m looking forward to it.
“But that’s only part one of the plan really because then it’s kind of been decided to try and go to the Tour.”
Thomas raced both in 2017 but crashed out in both.
“Hopefully this year’s a bit better than that,” the 2018 Tour de France winner added.
“I really wanted to do that [the Tour] and I really wanted to do the Giro, so I was speaking to the team in December and they were like ‘yeah we’ll back you’, but we need to get it cleared by Dave [Brailsford] and Jim [Ratcliffe], the big bosses basically.
“They’re all for it so happy days.”