The first generation of the BMW 1 Series consists of the BMW E81 (3-door hatchback), BMW E82 (coupe), BMW E87 (5-door hatchback) and BMW E88 (convertible) compact cars. The E81/E82/E87/E88 generation was produced from 2004 until 2013 and is sometimes collectively referred to as the E8x. The E8x replaced the 3 Series Compact as the entry-level models of the BMW range.

The chassis has an aluminum multi-link suspension, and a rear-wheel drive layout with a longitudinally-mounted engine giving 50:50 weight balance, which was a rare configuration for a hatchback as most cars in this market segment use front-wheel drive. The engines available were four-cylinder turbo-diesel, four-cylinder naturally aspirated petrol, six-cylinder naturally aspirated petrol and six-cylinder turbocharged petrol (the latter only available on coupe and convertible models).

The highest performance trim is the 1 Series M Coupé which was powered by the BMW N54 turbocharged inline-six engine mated to a six-speed manual transmission. It was produced in only the coupe body style and is considered the predecessor to the BMW M2.

Following the introduction of the F20/F21 1 Series in 2011, the E81/E87 hatchback models began to be phased out, while the E82/E88 coupes and convertibles remained in production until 2013, when they were replaced by the F22/F23 2 Series models.