Athleisure is a hybrid style of athletic clothing typically worn as everyday wear. The word is a portmanteau combining the words "athletic" and "leisure". Athleisure outfits can include tracksuits, sports jackets, hoodies, yoga pants, tights, sneakers, flats, Birkenstocks, uggs, leggings and shorts that look like athletic wear or pair well with it. Characterized as "fashionable, dressed-up sweats and exercise clothing", athleisure grew during the mid-2010s, from the popularity of yoga pants that emerged throughout the mid to late 2000s. The athleisure trend entails casual clothing options that give North American women the option to incorporate athletic clothing as part of their everyday attire, irrespective of their actual engagement in physical activities.

Athleisure is a contemporary fashion industry movement, enabled by scientific development and growth of advanced and cutting-edge textile materials and technical fabrics and fibers which allow modern activewear to be more durable, breathable, lightweight, stretchy, versatile, comfortable, and fashionable. Since the mid 2010s, it is also recognized as a retail clothing category.

In the 1930s, the American sportswear company Champion began producing hoodies for American working-class laborers working in freezing temperatures. In 1958, the American chemical maker DuPont invented spandex, a crucial material component foundational in many pieces of contemporary athleisure. The German sportswear company Adidas popularized athletic fashion by introducing sport-to-street tracksuits in 1963. By the 1970s, athletic fashion was ubiquitous throughout North American street culture which grew in popularity throughout the 1980s from old school hip hop music videos.

By some accounts, the growth of the modern athleisure trend took root and became more pronounced during the mid-2010s, which itself grew out of the popularity of yoga pants that emerged throughout the mid to late 2000s. Springing from the convenience of wearing clothes allowed North American women to casually wear yoga pants for multiple occasions without having to frequently change. Its popularity may have also stemmed from its ability to fill a gap in the sportswear market, when athletic apparel was once merely utilitarian rather than for cosmetic and fashionably stylistic purposes. Another account suggests that the cyclical nature of blue jean sales has allowed athleisure apparel to supplant denim as casual wear. Activewear that had been worn exclusively in gyms is now being casually worn elsewhere by young adults and fitness-conscious consumers and has been accompanied by a relaxation in dress codes. The styles, colors, and fabrics of athleisure postulate a broader emphasis on being fashionable as opposed to functionality. Technological advances in textiles innovation have brought improvements in functionality, such that modern garments and footwear have become more breathable, lightweight, stretchy, versatile, comfortable, fashionable, durable, and waterproof. Contemporary garments are performance enhancing and allow wearers to carry out everyday activities easily.

By 2020, a so-called "next-gen athleisure" category had emerged, owing to increasing acceptance in the workplace as well as advancements in fabric and production technology, which has led yoga pants to also function as an acceptable form of officewear. The COVID-19 pandemic contributed to a continued increase in the popularity of athleisure wear. Some fashion brands that had previously made streetwear or suits pivoted to items like hoodies and jogging trousers, since many people were quarantined at home and wanted comfortable clothing that would still look stylish for virtual meetings.

Athlingerie (athletic lingerie) is a hybrid fashion concept that merges the functionality of athletic wear with the aesthetic appeal of lingerie. This emerging trend focuses on versatile designs that offer both performance and sensuality, catering to modern lifestyles that demand multi-functional and inclusive apparel.

The concept of athlingerie grew alongside the broader athleisure movement, which blurred the lines between activewear and everyday fashion. Athlingerie takes this a step further, integrating delicate fabrics, lace, and form-fitting silhouettes traditionally associated with lingerie into the technical and performance-driven designs of athletic wear. The term first began appearing in print around 2016. Designers like Alexander Wang, Victoria Beckham, and Yotam Solomon incorporated similar elements in their early explorations of functional luxury, blending style with wearability.

The trend reflects shifts in consumer behavior toward adaptable, body-positive fashion that transitions seamlessly from fitness routines to casual or intimate settings. By the early 2020s, the concept gained traction as brands sought to create apparel that fused utility and sensuality in response to evolving market demands with major influencer based brands such as Skims and Savage X Fenty launching products in the athlingerie space.