She will play the character of Michonne in the zombie drama's second season finale, according to Hollywood Hills.
A fan favourite from the original Walking Dead comic, Michonne has a mysterious past and fights off flesh-eating walkers with a katana.
Wesley is best known for playing Tara on True Blood and will next be seen in Ridley Scott's sci-fi blockbuster Prometheus.
Her casting on The Walking Dead is yet to be confirmed by AMC or other official sources.
Series creator Robert Kirkman recently revealed that new characters will join the show in the near future.
Norman Reedus, who plays Daryl Dixon, has also promised that future episodes will be "more action packed".
The Walking Dead will return in early 2012 to AMC in the US and FX in the UK.
> The Walking Dead named top-rated cable drama
Watch a preview for the return of The Walking Dead below: