The Free Fallin' singer, 66, suffered a fatal cardiac arrest in October just days after completing a 40th anniversary tour.
In a statement on his official Facebook page, Petty's widow Dana and daughter Adria revealed the results of a coroner's report into his death.
They said Petty had "passed away due to an accidental drug overdose as a result of taking a variety of medications".
"Unfortunately Tom's body suffered from many serious ailments including emphysema, knee problems and most significantly a fractured hip," their statement said.
"Despite this painful injury he insisted on keeping his commitment to his fans and he toured for 53 dates with a fractured hip and, as he did, it worsened to a more serious injury.
"On the day he died he was informed his hip had graduated to a full on break and it is our feeling that the pain was simply unbearable and was the cause for his over use of medication."
Petty's family said he had been prescribed various pain medications including Fentanyl - the powerful painkiller which was also linked to Prince's death.
"We feel confident that this was, as the coroner found, an unfortunate accident," they added.
Dana and Adria Petty said they hoped revealing the findings of the coroner's report would help save lives by sparking a "healthy and necessary discussion" on the "opiod crisis".
"Many people who overdose begin with a legitimate injury or simply do not understand the potency and deadly nature of these medications", they said.
They added that Petty had died "painlessly and beautifully exhausted after doing what he loved the most" following his 40th anniversary tour with his band, The Heartbreakers.
"He was extremely proud of that achievement in the days before he passed," the family said.
"We continue to mourn with you and marvel at Tom Petty and the Heartbreakers' incredible positive impact on music and the world. And we thank you all for your love and support over the last months."
Petty, whose hits included American Girl, Free Fallin', I Won't Back Down and Don't Come Around Here No More, suffered a cardiac arrest at his Malibu home and could not be revived.
His worldwide record sales topped 80 million and he and The Heartbreakers were inducted into the Rock Hall of Fame in 2002, described as "the quintessential American individualists".
Bob Dylan, who performed with Petty in the supergroup The Traveling Wilburys along with Roy Orbison, George Harrison and Jeff Lynne, described his death as "shocking, crushing news".
(c) Sky News 2018