Initiated by UN women and launched by ambassador Emma Watson, the campaign was grounded in the idea that gender equality is an issue that affects all people, and it shouldn't by a struggle by women, for women.
Elizabeth Nyamayaro, head of HeForShe has been part of it from the very beginning.
Yet in January 2015, its success showed that an awareness campaign was not enough.
Something more concrete had to be done.
So, IMPACT 10X10X10 was launched in January, and in May 2015, 30 world leaders stepped up globally to support it. It was the movement that took HeForShe to a whole new level - a movement that would initiate change.
"When I was growing up in an African village, I saw the power dynamic play out in interesting ways," Nyamayaro told HuffPost UK Lifestyle when explaining why the campaign was personal to her.
"Women did most of the hard work as you know but when it came to making decisions, that was really made by men," she said.
"Fast forward a few decades later, I realised we need to not just look at the issue of gender equality as a woman issue, but understand the power dynamic still exists between men and women."
Nyamayaro said if the world was really going to address inequality, men had to be part of the solutions.
"The campaign came a bit from my own personal upbringing in Africa, as well as the realisation that we had to achieve clarity for box sexes."
She said she never expected HeForShe to grow as big as it has, describing it as an "interesting and humbling journey".
"We had no idea when we launched how this was going to be perceived because traditionally this has been a woman issue lead by women for women," she explained.
"We were coming with a new approach and trying to introduce men as a critical component to finding a solution.
"There were two things people were saying: we don't need men because they are the problem, and the second is that men actually don't care."
But something incredible happened.
Initially setting a goal of 100,000 men to sign up to HeForShe to pledge their support, Nyamayaro said they put no time limit on achieving this goal.
But within three days, more than 100,000 men had signed up at HeForShe and committed to be advocates for change.
"Within that first week, at least one man in every single country in the world had stood up for the cause," she explained.
"We ended up with 1.2 billion conversations on social media and that's when we realised, we were tapping into something that both men and women were ready for and we needed to set ship with this dialogue."
But by far the woman who has had the biggest impact on the campaign, Nyamayaro said, was Emma Watson.
Launching the campaign as UN Women Goodwill Ambassador, Watson delivered a powerful speech at the event in New York to tell the world why it was a worthy cause.
"She was so passionate about and it was a personal thing for her," Nyamayaro explained. "We went to launch with no PR, nothing on social media. Everything relied on that speech.
"Her speech ended up creating a phenomenal global movement over night.
"I don't think we would have had the same impact without the authentic voice and passion of Emma Watson.
"We even had letters from men from prison saying 'I saw her speech and it really moved me and it's something that I always felt that I need to be part of a solution to but I didn't know how to'."
But Nyamayaro said she also had to give a lot of credit to the head of UN women, Phumzile Mlambo-Ngcuka.
"Without a visionary leadership and freedom fighter, I don't think we would have done something as brave as saying we are UN women but we are going to come out with an agenda that really is about men."
After the initial launch that prompted thousands of daily emails into the HeForShe inbox, the team soon realised that the idea of having a year-long awareness campaign was just not enough.
Nyamayaro said all they were going to do was simply start a conversation, but people began asking them what else they were going to do to push for gender equality globally?
"There were impact stories from all over the world, in particular I remember one from a man Zimbabwe who, after signing HeForShe, said he went around his village, handpicked all the men and literally set up a husband school.
"He said as part of my commitment I am going to make these men into better husbands and fathers. There were numerous stories like this."
Nyamayaro said there was an "overnight pressure". She was being told "you have created this campaign, but awareness is simply not enough. You can't create a mass movement, and just call it an awareness campaign".
So she went back to the drawing board and came up with the pilot initiative: IMPACT 10X10X10. The three-to-five year pilot movement includes ground-breaking commitments from heads of state, CEOs and university presidents.
The initiative includes 10 heads of state, 10 CEOs and 10 university presidents all making commitments on how they will achieve gender equality in their corporations.
The global leaders include Barclays, Oxford University, Vodafone and Twitter.
"The most important thing for us was to be able to say, if we identify 10 leaders out of these three spheres, can we create a pilot initiative that starts to create the best gender equal country and company in the world?" explained Nyamayaro.
"And that's the IMPACT 10X10X10 - how can we move this discussion from promoting to advancing to really achieving equality.
"We need to make sure this momentum, which happens once in a lifetime, is taken with a high level of responsibility. We might not get this opportunity again."
Selecting the leaders to be part of the initiative was a highly-selective process. Many heads of state and members of the EU council had already emailed to ask how they could help.
Nyamayaro said they asked each and every person to concretely give a game-changing commitment, and came up with a selection criteria.
"We said you have to be able to give us three, concrete and NEW game-changing commitments. We had interest from close to 100 companies and had to set the bar really high and it became a highly selective process to pick the 30 people."
Commitments (full list below) include closing the gender pay gap by 2022 and achieving one-third representation of women across all university senior leadership roles by 2020. But are these realistic?
"We have had a very rigorous process and I feel confident we can deliver them," Nyamayaro told HuffPost UK Lifestyle.
"We had commitments that weren't realistic and did not make this list. I thought how are we going to achieve this? We then came up with a mandatory auditing that happens on an annual basis.
"We are going to be publishing an annual report until 2022.
"There will be a report in December to talk about what we have done in this year alone, that's another monitoring and evaluation tool for us.
"We are going to publicly share this annually for the whole world to see.
"The commitments are from the CEO so we are working with the men that have the power to implement this change and I think this will push them to want to do better, because they are competitive!"
When asked what pledge was most personal to her, Nyamayaro said it's hard to choose.
She said: "I think the exciting thing for me is to see that we have been able to cover most of the big issues we are still facing - violence, equal pay, employment, that excites me.
"More than anything else, it's to see our champions collectively tackling all of the important issues that we think needs to be addressed.
"We want men to own it. We are revamping the website and launching a new one in September which is going to be interactive and dynamic and will be able to share things on what men can do as well as share other impact stories we have been collecting.
"If you're a man, question everything, if you're employed have a discussion with your boss: are women getting the same equal pay as me?
"Be an active participant on the diaglogue in gender equality.
Over next couple of months, Nyamayaro is focusing on the implementation of the new movement, which an exciting surprise launching in September.
She said the next phase is going to be much more inclusive for all of us, including women and girls this time.
"It's a solidarity movement, we don't want to lose women, we want to be able to rally all of society and continue as HeForShe, but integrate women's voice.
"I can't stress that enough because we have no choice but to succeed and we must succeed."
GOVERNMENT COMMITMENTS MADE:
Close the gender pay gap by 2022, and achieve gender parity in the media by 2020. —Sigmundur David Gunnlaugsson, prime minister, Iceland
Reach at least 30% representation of women in parliament and improve women’s representation in other decision-making processes. —Ir. H. Joko Widodo, president, Republic of Indonesia
End child marriage. –Arthur Peter Mutharika, President, Republic of Malawi
Launch the first nationwide analysis to end violence against women. –Klaus Werner Iohannis, President, Romania
Close the gap between men and women in employment. –Stefan Lofven, Prime Minister, Sweden
CORPORATE COMMITMENTS MADE:
Reach 2.5 M women around the world with financial inclusion programmes. —Anthony Jenkins, CEO, Barclays
Reach 150,000 employees with pay equity by 2017. —Jean-Pascal Tricoire, CEO, Schneider Electric
Bring mobile education 3M to refugee girls in Vodafone markets by 2020. —Vittorio Colao, CEO, Vodafone Group Plc
UNIVERSITY COMMITMENTS MADE:
Achieve one-third representation of women across all university senior leadership roles by 2020. —Professor Andrew Hamilton, vice chancellor, University of Oxford
Close the gap between men and women—from matriculation to graduation—by 2020. —Samuel L. Stanley, Jr., president, Stony Brook University (SUNY-Stony Brook)
Establish and implement a zero-tolerance policy to address and prevent violence against women on the USP campus. —Dr. Marco Antonio Zago, president, University of São Paulo
Reach 40 percent representation of both genders in academic, administrative and senior leadership positions by 2020. —Frédéric Mion, president, Sciences Po