Earlier this year the X-Men star was confirmed as the adult version of Bill, last seen played by Jaeden Lieberher in the It movie.
Set 27 years after the events of the first film, It: Chapter 2 sees the Losers Club all grown up in present day.
But when news of Pennywise once again wrecking havoc on the children of Derry, Maine comes apparent, the group return to take him down once more.
Now the shoot has finally begun on It: Chapter 2, as confirmed by the first set photo taken by McAvoy himself.
Posted yesterday, McAvoy wrote on his official Instagram: “Day 1 on IT 2.
“Glad you got the memo guys #passthecheeseplease #derryordairy.”
The picture itself was a shot of the star reflected in a mirror holding a triangle piece of The Laughing Cow cheese.
Sadly McAvoy’s snap doesn’t reveal anything about It: Chapter 2 apart from a poor pun.
The star is joined on It: Chapter 2 by Jessica Chastain as Beverly Marsh and Bill Hader as Richie Tozer.
These three film star leads were followed by a group of TV actors to make up the supporting cast.
This included another couple announced at once in the form of James Ransone as Eddie Kaspbrak and Andy Bean as Stanley Uris.
As for Ben Hanscom, a character who goes from chubby kid to handsome hunk, it was Jay Ryan who bagged that role.
And last but not least is Isaiah Mustafa as Mike Hanlon, who was announced over the weekend.
Meanwhile Bill Skarsgard is returning as Pennywise and the Swedish star has teased It Chapter 2.
Speaking with Den of Geek, Skarsgard said: “We’re gearing up for it now, so I’m sort of in the process of getting back into that character of Pennywise. I’m sort of in the mindset and we’re gearing up for it.
“I think they [the Losers Club cast] start in July. I’m not sure exactly when my start date is, but some time this summer.”
It: Chapter Two will be released in UK cinemas on September 6, 2019.