Ward, a former Aston Villa trainee, has now committed to the Rams through to the summer of 2016.
The Northern Ireland international is the seventh player to sign on for an extended stay at iPro Stadium this summer, following in the footsteps of Jeff Hendrick, Craig Forsyth, Jake Buxton, Will Hughes, Craig Bryson and Mason Bennett.
Head coach Steve McClaren told www.dcfc.co.uk: "We're happy that Jamie Ward has become the latest player to sign a new contract with Derby County.
"He has proved to be an important player for us during the last year and it's pleasing he has re-committed to the cause.
"He is a threat to opposition defences and is a strong attacking option for us in the formation we play."
After spells with Stockport, Torquay, Chesterfield and Sheffield United, Ward first joined Derby on loan in January 2011 and quickly made the move a permanent one after five goals in 13 appearances made him a fans' favourite.
The 28-year-old made 42 appearances in all competitions last year, scoring seven times, as he played a key role in an impressive third-placed finish which ultimately ended in Championship play-off final heartache.