The star said he felt he "shouldn't be doing it" because his late friend Cilla Black had originally hosted the show.
"I thought 'This isn't right, it's so synonymous with Cilla, she should be here, not me,'" he told Radio Times.
"But then I spoke to her sons and lots of people who knew her and they said 'You have to do it, because she'd want you to do it for everyone.'"
Black, who died in August 2015, hosted the ITV dating show from 1985 until 2003.
O'Grady said the pair had bonded over their working class Liverpudlian roots.
"We knew where we were both coming from," he said. "We both knew what outside loos were. All the stereotypical stuff."
O'Grady said it was more difficult to interview contestants than celebrities.
"You're interviewing the public, so they're not as confident. You have to be easy on them."
Blind Date, which will include LGBT contestants for the first time, begins on Channel 5 on Saturday 17 June.
The original ITV version of the show involved three individuals of the same sex being introduced to the audience. They were then asked questions by a contestant of the opposite sex who could not see them - and one would be chosen to go on a date,
The new format will retain the sliding panel that conceals the contestants, the three question format and live studio audience, but will also include "thematic twists" to "breathe new life" into the series, according to Channel 5.
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Paul O'Grady says "it was a shock" when he first filmed the upcoming revived version of Blind Date.