An Adirondack chair is a type of chair used primarily in an outdoors setting. The first Adirondack chair was designed by Thomas Lee in 1903. He was on vacation in Westport, New York and he needed outdoor chairs for his summer home. He tested the first designs on his family.

The original Adirondack Chair was made with eleven pieces of wood, cut from a single board. It had a straight back and seat, which were set at a slant to sit better on the steep mountain inclines of the area. It also featured wide armrests which became a hallmark of the Adirondack Chair.

The Adirondack Chair might have stayed in Lee's back yard, except for his friend Harry Bunnell . Bunnell had a small carpentry shop and needed a source of winter income. He used Lee's idea and started to create the chairs.

In 1905, Bunnell received a patent for the "Westport Chair". For the next twenty years, Bunnell produced these chairs. All of his "Westports" were signed, made out of Hemlock and painted green or dark brown.

The Adirondack Chair has changed over the years, while maintaining the same style and comfort. Today's Adirondack Chairs usually feature a rounded back and contoured seat. The style has also been translated to other pieces of furniture, anything from Gliders to Love Seats. Some modern adirondack chairs can be made out of recycled plastic lumber in addition to wood.

In Canada, it is often called a Muskoka chair, named after an outdoor recreational region in southern Ontario.