Conceived as a hidden oasis in the city, Hotel Rosalie is set in a courtyard behind a tall iron gate on a tree-lined street in the 13th arrondissement.
Greenery is incorporated into every aspect of Mailaender's design for the 60-room hotel, including a plant-filled terrace and a hidden roof garden.
Parisian urban gardening collective Merci Raymond was brought on board by Bruneel to make the hotel's outdoor spaces seem "overgrown" and help nature "reclaim its rightful place in the urban landscape".
Bruneel was particularly influenced by Urbex, a series of images by French photographer Romain Chancel that is displayed in the hotel's guest rooms and depicts abandoned urban buildings that have slowly been reclaimed by plants.
In a nod to this work, Merci Raymond encouraged lichen and moss to grow and seeds to germinate in the hotel's nooks and crannies. Meanwhile, Mailaender incorporated urban design elements into the scheme ranging from "Roman-style statues" to an old Peugeot 205 car that is seemingly left abandoned on the rooftop.
On the ground floor, the hotel's Open Garden is accessible to the local community and features steel outdoor furniture by Ronan & Erwan Bouroullec set across a two-level terrace linked by a little staircase.
A towering six-metre hop plant provides shade while its flowers will be used by a microbrewery in the 11th arrondissement to make beer.
The hotel's Secret Garden lies behind a hidden door on the third floor. This is furnished with deck chairs, wooden benches and planters, offering a space where guests can read, relax in the sun, do yoga classes or participate in workshops organised by the hotel.
Inside, Mailaender has included plenty of nature-inspired elements. In the lobby, a giant coconut-fibre rug leads guests inside while armchairs and couches by Italian architect Gae Aulenti are upholstered in clover-patterned pop art fabric.
Meanwhile, guest rooms feature galvanised steel furniture, which is typically used outdoors, and floral William Morris carpet that extends up from the floor and across the headboards.
The interior blends new and reclaimed pieces in an approach that Mailaender describes as "intentional ambivalence".
In the bathrooms, for instance, traditional baths are paired with counters made from terrazzo-style recycled plastic.
All materials were chosen for their aesthetic as well as their environmental impact, according to Mailaender.
For example, the carpet in the guest rooms is made from recycled fishing nets and wood offcuts were used to make a marquetry tabletop in the lobby.
Cork clads the restaurant's floor and the walls of the elevator, and many of the chairs are pre-owned pieces that were carefully restored.
"I believe that we can mix furniture designed by the Bouroullec brothers with random pieces from a gardening catalogue," explained Mailaender. "Embracing current concerns means selecting sustainable materials alongside aesthetically pleasing design pieces."
The hotel has its own coffee shop The Common, finished in a distinctive blue hue that nods to 90s air hostess uniforms.
This colour is echoed on a glossy pillar in the bar, a trellis in the secret garden and on the guest room doors, where it offsets the grass-green carpet that winds through the hotel corridors.
Dezeen recently rounded up ten verdant hotel interiors from our archive that show how adding greenery to public spaces can help give them a friendlier, more organic feel.
The photography is by Christophe Coenon unless stated otherwise.