Stella McCartney's presentation at Milan Fashion Week Men's Spring 2020.

LONDON — Goodbye, François-Henri. Hello, Bernard.

In a deal that speaks to grand ambitions in the sustainability space and protecting the planet — and a major leap from one luxury titan, François-Henri Pinault and Kering, to his larger rival, Bernard Arnault — LVMH Moët Hennessy Louis Vuitton has surprisingly taken a minority stake in the house of Stella McCartney. It also has tapped the green campaigner as a special adviser to LVMH chairman and chief executive officer Bernard Arnault and the executive committee members.

Having launched a Millennial-focused luxury maison with Rihanna under the Fenty label earlier this year, LVMH is now planting its flag firmly in the fields of green: Not only will the luxury giant support the growth of McCartney’s brand, it plans to give the designer, who has described herself as an “eco-weirdo,” carte blanche to preach the environmental gospel at LVMH.

While LVMH has long been committed to environmentally aware practices, it has been shy about touting its credentials, unlike some of its competitors. Yet it was the first large company in France to create a sustainability department, more than 25 years ago, and during its 2019 annual general meeting, it outlined its goals in eco-design, the responsible supply chain, combating climate change and improving the environmental performance of sites and stores.

Now, with Stella on board, it’s ready to roar.

Arnault said he was “extremely happy” about the partnership, and a decisive factor in the deal was McCartney’s early decision “to put sustainability and ethical issues on the front stage, and built her house around these constraints. It emphasizes LVMH Group’s commitment to sustainability.”

The luxury titan called Monday’s announcement “the beginning of a beautiful story together, and we are convinced of the great long-term potential of her house.” Although LVMH tends to take majority stakes or buy companies outright, it sometimes structures deals differently, working with partners or taking minority stakes, as it did with Jonathan Anderson and his JW Anderson brand.

For her part, McCartney got just what she wanted: She has retained a majority stake in her company, while under former partner Kering she had a 50-50 deal. She also has a new business partner who will be as, if not more, supportive on the eco-front, and that is key as sustainable practices don’t come cheaply.

In fashion and luxury, McCartney has been at the forefront of helping to source and develop textiles and manufacturing processes that are animal-friendly and sustainable. She was one of the first Kering brands to undertake an environmental profit-and-loss audit, which sees a company measure its impact on the environment.

She dubbed her women’s 2020 resort collection “Force of Nature” and the men’s spring 2020 collection “Eco Weirdo.”

“I think that’s important to take on board that we are still weirdos to the majority of the world, and we are fine with that. I am fine with being a weirdo, and it will probably never change,” said the buoyant designer during a walk-through of both collections last month in London.

T-shirts shouted “Eco Weirdo,” “Handle With Care, You’re Holding Planet Earth” or “SOS,” while fabrics included a type of viscose that was three years in the making, organic cotton, regenerated cashmere and nylon. Bags were made from eco Alta Napa leather and PVC was nowhere to be found. Since 2010 all products — both from Stella McCartney and the brand’s collaboration with Adidas — have been PVC-free.

McCartney said at that time that she always starts with the soil. “It is a big conversation with whomever we want to work with. Animal welfare is first and foremost. How are you are nurturing the soil? How do the animals live in their environment? At the end of the day, fashion is farming and it is raping the environment,” she said.

While it is understood that McCartney’s friendship with Arnault’s eldest son, Antoine Arnault, the ceo of Berluti and chairman of Loro Piana, helped to seal the deal, LVMH’s own green ambitions were also a clincher.

McCartney said Monday that nothing could match the conversation she had with Bernard and Antoine Arnault before she signed. “The passion and commitment they expressed toward the Stella McCartney brand alongside their belief in the ambitions and our values as the global leader in sustainable luxury fashion was truly impressive.

“The chance to realize and accelerate the full potential of the brand alongside Mr. Arnault and as part of the LVMH family, while still holding the majority ownership in the business, was an opportunity that hugely excited me.”

While Stella McCartney’s full revenue was never disclosed and always consolidated onto the Kering balance sheet, it is thought to be about 300 million euros. The company’s valuation when it split from Kering was estimated to be about 600 million euros, according to sources.

Melania Grippo, luxury analyst at Exane BNP Paribas, said the partnership with LVMH “should speed up the development of the brand, which aims to remain faithful to its commitment to sustainable and ethical luxury fashion.”

Grippo added that the transaction would have a limited impact on LVMH’s accounts — less than 1 percent of total sales — and that LVMH “has confirmed once again its ability to attract, nurture and develop brands.”

The deal, a win-win one for LVMH and McCartney, came as something of a surprise.

McCartney had been 50-50 partners with Kering for 17 years. In an interview with WWD, McCartney had described the split as amicable and said their relationship would steam ahead, with the designer planning to remain a board member of the Kering Foundation and continuing to collaborate with the French luxury giant on sustainability in fashion.

Those plans will likely have been undone by the LVMH deal. A McCartney spokesman did not return phone calls at press time, and a Kering spokesman declined to comment.

Stella McCartney and Kering parted ways after the latter began restructuring its portfolio. McCartney’s contract gave her the option to repurchase Kering’s stake, exercisable by March 31, 2018.

In the end, the designer went for the buyout, deciding she didn’t want to hand over full control to Kering, or remain 50-50 partners. At the time, McCartney said she wanted to strike out as an indie brand and explore the possibility of new partnerships.

“I have had an incredible relationship with Kering, and first and foremost with the Pinault family, whom I consider to be great friends. I’m incredibly close to them. We had such a successful business together, an incredible partnership. We never had any hiccups,” said McCartney during an interview from her airy new offices near Westfield London.

Over the years, McCartney had worked closely with Kering on building values around environmental sustainability and best practice, and had been a promoter of the group’s five-year partnership with London’s Center for Sustainable Fashion to support eco-friendly practices and innovation in the fashion industry.

Last year, Kering and London College of Fashion revealed the creation of the first open-access digital course in luxury fashion and sustainability called “Fashion & Sustainability: Understanding Luxury Fashion in a Changing World.”

The separation deal with Kering was to have taken two years, with the first and most important phase ending on March 31 this year, and Kering helping the Stella McCartney business tie up loose ends in back-office operations, and make a smooth exit by March 31, 2020.

Over the past few months, McCartney’s longtime ceo Frederick Lukoff left his job to take up a similar role at the contemporary brand Scotch & Soda, while Stephane Jaspar quit his role as chief marketing officer to assume the position of chief brand officer of The Webster.

The closing of the partnership with LVMH is subject to the usual conditions, in particular the approval of the competition authorities. LVMH said it will reveal more details about the partnership in September.