The former Express journalist, left, was the clear favourite to succeed Mr Dear who decided earlier this year not to seek a third term in the role.
News of Ms Stanistreet’s election was confirmed in a Tweet by the union’s president Peter Murray this afternoon.
He wrote on his Twitter feed: “Michelle Stanistreet confirmed as next GeneralSecretary of #nuj First woman in the post. Congratulations. A Luta Continua.”
Ms Stanistreet, who is currently deputy general secretary, will take over the top job on 1 July.
The only other candidate, Coventry-based freelance Chris Youett, withdrew from the race and backed Ms Stanistreet.
Following her election, she said: “I am immensely proud to be elected to lead our union – and to be the first woman to have the opportunity to do so.
“I will repay the faith placed in me by working hard to build our union, speak up for members and stand up for journalism.”
Mr Dear said: “The union is in the best possible hands. Michelle has been a fantastic deputy and has always fought resolutely to defend journalists and journalism.
“She will work tirelessly on behalf of all members and to ensure the NUJ is and remains the voice of journalists in the workplace and throughout the industry.”
The union is holding its annual delegate meeting (ADM) in Southport this weekend.