The England midfielder has penned a four-and-a-half year contract to commit himself to the club until 2019.
He was out of contract in the summer and had been linked with a move away from the Barclays Premier League strugglers, who have battled relegation for the last three years.
Boss Paul Lambert called it a coup for Villa and Delph revealed even the squad was surprised.
"The lads are absolutely delighted
As soon as I told some of them they looked at me shocked to start with," he said.
"They see a lot in me and how dedicated I am and how I want to push on
They're delighted to keep someone like me here.
"I see them as family, brothers, I'd run through a brick wall for them
They're not just team-mates."
Villa chief executive Tom Fox played a key role in convincing Delph to stay and believes the 25-year-old has bought into his vision.
"We are so pleased to keep one of our best young players
It says a lot about him too and his faith," said Fox.
"This club is on a journey and it's my job to talk to as many people and convince them it's not where we are.
"Fabian and I have had many conversations and he believes in this journey
There were a lot of interested clubs
We've got a top young player here.
"The top five clubs are in a much better place financially."
Source : PA