A jersey is a piece of woollen or cotton clothing with sleeves worn as a pullover; this is to say, it does not open at the front, unlike a cardigan. It is usually close-fitting and machined knitted in contrast to a guernsey that is more often hand knit in a thicker cloth. The word is usually used interchangeably with sweater and is the name always officially used in the United Kingdom to refer to the item when worn as part of the uniform of military, police or other uniformed personnel.

Alternatively, a jersey as used in sport is the name of a shirt worn by a member of a team, usually oversized, typically depicting the athlete's name and team number as well as the team's logotype or corporate sponsor. Notably, jerseys of specific colour or pattern represent certain statuses in cycling - such as the yellow jersey of the leader of the Tour de France.

Jersey is also a soft, slightly elastic cloth made from wool, cotton or silk.

The name derives from Jersey, the largest of the Channel Islands, where the material was first produced.