The former deputy party leader has called for men to sit out the battle to succeed Jeremy Corbyn whenever it comes.
Ms Harman said her idea was “startling” a lot of would-be leaders, whom she claimed were laughing at the initiative.
She told The House: “Next time I think we have to be quite clear about this and basically say there are lots of fantastic men in the Labour Party who would be more than capable of being leader.
“There’s no doubt about that and there are also lots of women who are more than capable of being leader, and we’re going to choose one of the women.
“The men can jostle amongst themselves to be deputy.”
Ms Harman said senior male figures should do more than just sit out the contest by actively supporting a woman to be the next leader.
“They’ve got to be holding themselves and each other back in support of the Labour Party getting a woman leader,” she said.
“Because the Tories have had not one, but two women leaders. So it’s becoming a bit of a thing.
“At the moment, I’m advancing this argument and I’m not saying I’m making a huge amount of progress with it.
“I’m startling a lot of the would-be leaders and they think I’m joking and peel away with laughter and I’m, like, deadly serious.
“You’ve had women saying there should be a woman leader. You’ve had men saying there should be a woman leader, but we haven’t yet had the men who are potential leaders saying, ‘this time it’s a woman’. That’s the next step.
“And so, the next generation of men need to be those remarkable men who actually support women leaders.”
Ms Harman signalled she would consider standing for the post of Commons Speaker when incumbent John Bercow leaves the role.
She said: “People have been asking me whether I would be prepared to stand. But I think that that’s something that I would have to consider when there’s a vacancy, and there isn’t one at the moment.”