Delph joined the club in 2009 but has struggled to make an impact due to several long-term injuries.
He told reporters: "This is my first season that I've actually been fully fit. I've had some terrible injuries. This has been my best spell since I've been here.
"I've been here a long time and, for me, it is personally about paying back the faith the chairman has put in me and also the faith the manager has put in me."
The 23-year-old will miss Villa's games against Reading and Queens Park Rangers in the next two weeks after picking up his 10th booking of the season against Manchester City.