The six-part series will appear on the network's website in its entirety on Monday, October 3, several weeks before the second season of the survival horror show is due to air.
Nicotero's webisodes will focus on the zombie dubbed "Bicycle Girl", who appears in the first season as an emaciated torso before being killed by Andrew Lincoln's Rick Grimes.
AMC said in a statement: "The webisodes will give fans the opportunity to explore the back story of Hannah (Lilli Birdsell), better known as 'Bicycle Girl', the infamous zombie from season one, who was shot by Rick Grimes (Andrew Lincoln) in the pilot episode and who is one of the most celebrated "walkers" from last season.
"Fans will learn about Hannah's life before the apocalypse, her struggle to survive and protect her family as the world begins to fall apart, and her ultimate demise into zombie-hood."
A talk show dedicated to the series, Talking Dead, will air alongside season two. The Nerdist host Chris Hardwick was confirmed as the presenter on the programme.
The Walking Dead will return to AMC in the US and FX in the UK next month.
Watch a promo for the return of The Walking Dead below: