The 26-year-old Brazilian made 36 appearances for the Robins last season as they were relegated from the Ryman Premier.
Moraes signed on the dotted line at the Waterside stadium last Tuesday night, having turned out in a 3-0 defeat to Kingstonian the weekend before.
While the Robins have fallen down the non-League pyramid, the Casuals are making big noises about going in the other direction – something Moraes found hard to resist.
He said: “People will say Carshalton is the bigger club, and they are probably right, but Walton Casuals have a passion and a drive to succeed that won me over.
“It was a tough decision because I had a great time at Carshalton, especially off the pitch, and the people there are great.
“But I want to start playing football for the pleasure and excitement of winning again, and I could not see that happening at Carshalton.
“I spoke to Stuart [Massey, Carshalton manager] at the end of last season and asked what his plans were, and he said he did not know.
“They are not settled, they had three managers last year. I cannot go through that again.”
As a 17-year-old, Moraes signed forms at Stoke City, and has also spent time at Feyenoord in Holland and Anderlecht in Belgium.
He arrived at Carshalton via Walton & Hersham, where his first full season was blighted not only relegation, but also three red cards.
So this term, the student of economics and finance at Birkbeck College, London, is looking to show what he is capable of.
Once, twice, three times the red card: Adriano Moraes, number five, sees red in September's defeat to Harrow Borough
“I want to show people how well I can play,” he said.
“I had too many suspensions last season, and I know I let the club down, but in a winning team, I know I can do better.
“I am desperate to win things. I won’t be playing football forever, and time is running out.
“Mark [Hams] said he knew all about my red cards and that he would not accept that, so we know where we stand.”