Duff, 26, who released two singles 'Chasing the Sun' in July and 'All About You' earlier this month, took to Twitter to break the news, reported Us magazine.
"Guys hate to break this news but the album won't be out in October... You will have to wait a few more months. Love all the excitement though," she wrote on her Twitter page.
Duff gave no explanation for the delay of the fifth album. Her last album Dignity was in 2007.