Williams speaks of gratitude to Villa after joining Bristol City
The 20-year-old defender emerged through the Villa Academy to play in every round of the 2009-10 FA Youth Cup as Villa progressed to the final before losing to Chelsea over two legs.
He also made a significant contribution to Villa's success in the reserve league and NextGen Series in 2011-12 and the Republic of Ireland U21 international's form propelled him to the fringes of the first team.
"I want to make a career for myself and I'm grateful for the great start I've been given by Aston Villa and coming through the Villa Academy," Williams said.
"Bristol City were interested and it's a big club. I'm looking forward to the challenge.
"I needed to take this step. I hope it's the right decision.
"I have no issues dropping down to League One. The club's aim is to bounce back stronger and it's a great goal to have.
"I just can't wait to get going now and meet all the lads on Thursday. I'm a bit nervous but I'm certainly looking forward to it.
"I did my YT at Villa from the age of 16 and worked with the likes of Kevin Macdonald and Tony McAndrew.
"I've been playing reserve team football for the last three years and it comes to a stage when you want to play for the first team.
"I've also played for the Under-19s and Under-21s for Ireland. The next step is to play for the senior team; that's certainly the aim and hopefully this move will help in the long run."
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