She will become its patron, a role that will see her providing the trustees with knowledge, advice and suggestions.
"I have had a wonderful time being involved with the festival but this new role as patron means I won't be losing touch.
"I am passing the festival on to the next generation and feel it is in very capable hands," Ms Rosier-Jones said.
She paid tribute to vice-chairwoman and secretary-treasurer Val Cowan, who has also resigned. "Val has been my right-hand person almost since the beginning and I could not have done it without her," she said.
The next Whanganui Literary Festival will be held in 2015. Visit the website www.writersfest.co.nz or facebook.com/whanganuiliteraryfestival if you would like more information.