Dahl's daughter Lucy will accept the accolade on behalf of her father in a special episode of the children's TV show, to be aired on CBBC on Thursday.
Dahl much-loved works include Charlie and the Chocolate Factory, Matilda and The Twits.
Had he not died in 1990, the author would have been 100 on 13 September.
Thursday's programme will see science presenter Greg Foot recreate Frobscottle - the favourite drink of the BFG, or Big Friendly Giant.
The show will also feature a performance by the cast of the West End musical version of Charlie and the Chocolate Factory.
Only a handful of gold Blue Peter badges are given out each year, in recognition of bravery, inspiration, citizenship and outstanding achievements.
Lucy Dahl said it was "extraordinary" and "truly amazing" for her father to receive the accolade.
"When you read a book you create your own version of the story, and you create your own pictures in your own mind," she said.
"Dad felt that reading books was one of the most important things a child could do, because he felt that imagination was so important."
"Roald Dahl's literary magic continues to enchant generations of children and will do for years to come," Blue Peter editor Ewan Vinnicombe said.
"Blue Peter is honoured to be able to celebrate his remarkable imagination in this special show."
Previous recipients of the gold Blue Peter badge include US film-maker Steven Spielberg and the illustrator and children's author Chris Riddell.
Schools across the UK marked Roald Dahl Day on Tuesday by asking pupils to dress up as their favourite characters from his books.
Celebrations continue this weekend in Cardiff, which will be transformed into "The City of the Unexpected" in an arts event involving 6,000 participants.
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But with little separating the party from conservative New Democracy, a coalition government is likely.
Syriza's leader, Alexis Tsipras, called the snap poll after securing a multi-billion euro international bailout.
Whoever is elected will have to oversee austerity measures demanded by Greece's creditors as part of the deal.
Syriza supporters' gathered in central Athens for the party's final rally on Friday, in what Mr Tsipas said sent "a message of determination and victory".
"On Sunday, we're facing a crucial referendum - to put an end to old political system, protecting oligarchs and corruption," he tweeted.
At the final New Democracy rally, its leader Vangelis Meimarakis attacked Syriza's "false promises" in the run-up to the last election, when it pledged to end austerity.
"It's high time we did away with incompetence. The Syriza experiment ends on Sunday," he said.
At a debate earlier in the week, Mr Meimarakis proposed forming a grand coalition with Syriza but Mr Tsipras rejected it as "unnatural".
Most of the parties support the bailout. But one of those that does not - the far-right Golden Dawn - is predicted to come third.
Analysts say the migrant crisis on Greece's doorstep may bolster support for Golden Dawn, which is vehemently opposed to immigration.
Children's author Roald Dahl is to become the first person to be honoured posthumously with a gold Blue Peter badge.
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Final campaign rallies have been held in Greece ahead of Sunday's elections, with several polls giving left-wing Syriza a small lead.