The 75-year-old American completed his takeover of the south coast club, who fell from the Premier League to the lowest rung of the Football league and are now climbing back up, last August.
League champions in the 1948-49 and 1949-50 seasons, and FA Cup winners in 1939 and 2008, 'Pompey' went into administration in 2010 and endured three relegations before entering fan ownership.
"The story going down is an unbelievable story and the story coming back is an unbelievable story," Eisner, who left Disney in 2005, told reporters at a Leaders Sport Business summit at Chelsea's Stamford Bridge.
"They (the owning fan group) recognised overwhelmingly that they needed somebody but they had such a bad experience that any name on any piece of paper would have been frightening.
"Luckily my name is well researched. I hadn’t been to jail, not stolen any money, don’t sell arms. They were like an abused child. They thought 'Oh my god, not another guy'."
Eisner said passing through the Fratton Park turnstiles for the first time was like his first day at Disney Studios and felt his career in entertainment had prepared him for his new adventure.
"Everything I've done has been involved with storytelling and increasingly telling the story of sports," he said.
"All of our sports films had one constant theme -- the triumph of the underdog over seemingly insurmountable odds. This is a story we've told time and again in fiction. With Pompey, we hope to get it right in fact."
The new owner summed up his strategy as the same 'slow, steady and smart' approach adopted at Disney and hoped manager Kenny Jackett, who signed a two-year deal in June, would stay for a decade.
The immediate goals were renovating the historic stadium, providing an excellent match-day experience for families and fielding a solid team.
"Obviously we want to rise but we are not going to do it overnight," said Eisner.
"I want to do it in a sane way because I’ve seen them try to do it instantly and get themselves into debt and the ego gets in the way.
"When I presented to Portsmouth I said that if you want someone to come in and throw everything at it straight away and promise the Premier League tomorrow then I’m not your guy, don’t vote for me."