The first new generation Mini Hatch was introduced in late 2000, being the first model launched under the Mini marque after the original Mini was discontinued in the same year. In some European markets, the Mini One was powered by a 1.4-litre (85 cu in) inline-four version of the Tritec engine, but all other petrol powered Minis used the 1.6-litre (98 cu in) version. From 2004 through 2008, the soft-top convertible R52 was made.

There are numerous styling and badging differences between the models, including the Cooper S having a distinctive scoop cut into the bonnet. The Cooper S also has twin exhausts which exit under the centre of the rear valance. The non-S Cooper has more chrome parts than the Mini One and has a single exhaust. The Mini One D has no visible exhaust pipes at all.

In some markets, such as Australia and the US, only the Mini Cooper and Cooper S are offered. Other trim lines of note, sold in varying markets around the world, are the Mini Seven, Mini Park Lane, Mini Check Mate, and Mini Monte Carlo.

The Mini Hatch (US: Hardtop) was designed by Frank Stephenson, and drew inspiration from the original two-door Mini. Development of the car was conducted between 1995 and 2001 by Rover Group in Gaydon, United Kingdom and BMW in Munich, Germany. During this development phase, there was continual contention between the two design groups, especially concerning the positioning of the car; Rover wanted a straight economy car (which would also replace the Rover 100 Series, which had evolved from the Metro in a 1994 restyle), whilst BMW supported a small, sporting car. Plans for an all-new supermini to replace the Metro in the mid 1990s were shelved when Rover was sold to BMW in January 1994, with the existing Metro model gaining a restyle and a new designation.

The concept was originally unveiled at the 1997 Frankfurt Motor Show at a joint BMW/Rover press conference, with details of the Chrysler/BMW joint venture Tritec engine, and proposed trim levels including Mini Minor (not used) and the Cooper/Cooper S.

Ultimately, BMW prevailed, and in 1999, they assumed control over the entire project following the departure of BMW's CEO, Bernd Pischetsrieder. When BMW sold off Rover in 2000, it retained the Mini project, and moved the planned production site of the car from Rover's Longbridge plant, to BMW's Oxford plant in Cowley, Oxford, England. The team of designers working on the 2001 Mini had finished the full-sized clay mock-up of the Mini in plenty of time for a presentation to the board of directors. However, the American chief designer, Frank Stephenson, realised that the model did not have an exhaust pipe. His short-term solution was to pick up an empty beer can, punch a hole in it, strip off the paint and push it into the clay at the back of the car, which took just a few minutes.[9] The overall design for the mock-up was so good that the board members told him not to change a thing, resulting in the distinctive exhaust tip seen in production cars.

The first generation of the new Mini received a facelift in July 2004 for the upcoming 2005 model year. This was also when the new convertible was introduced; it was not available with the pre-facelift design. Aside from minor design changes (mostly up front) and improved equipment, the Rover R65 manual gearbox was replaced with a Getrag five-speed for the MINI One and Cooper.

The vehicles produced during the 2001 to 2006 model years included four hatchback models (UK and some international markets: Hatch, US: Hardtop, other markets just plain Mini): the standard "Mini One", the diesel-engined "Mini One/D", the sportier "Mini Cooper" and the supercharged "Mini Cooper S"; in 2005, a convertible roof option was added to the Mk I line-up. In November 2006, BMW released a facelift version of the Mini Hardtop as a 2007 model-year vehicle.

From March 2002, the Mini was exported to Japan and sold at Japanese BMW dealerships as well as Yanase locations. The car complied with Japanese Government dimension regulations and the introduction of the Mini coincided with several vehicles in Japan that exhibited a retro look that Japanese car companies were offering.

The names Cooper and Cooper S are the names used for the sportier version of the classic Mini, which in turn come from the involvement of John Cooper and the Cooper Car Company. The Cooper heritage is further emphasised with the John Cooper Works (JCW) range of tuning options. The John Cooper Works company also created a higher spec model of the Mini Cooper S, the Mini Cooper S Works. It has a higher volume exhaust and air filter, and uprated brakes and suspension, and different 17-inch (430 mm) wheels from the S models.

A race-prepared version, with rear-wheel drive, called the Mini Cooper S3, competed in the Belcar championship from 2002.

The Mk I Mini One, Cooper and Cooper S used some version of the Brazilian-built Tritec engine, co-developed by the US-based Chrysler and BMW; the Mini One D used a Toyota 1ND-TV diesel engine. In August 2006, BMW announced that future engines would be built in Great Britain, making the car essentially British-built again. Final assembly took place at Cowley, Oxford, and the body pressings were made in nearby Swindon at BMW's Swindon Pressings subsidiary.

All models used a transversely-mounted 4-cylinder engine driving the front wheels. All 4 wheels are pushed to the corners of the body to improve handling. The styling of the car, like that of the Volkswagen New Beetle, is a retro design that is deliberately reminiscent of the original Mini. The retro styling retains other classic Mini touches such as contrasting roof colours, optional bonnet stripes, optional rally lights, and black trim around the wheel arches and rocker panels that mimic the wide wheel flares found on many classic Minis.

The Mini One and Mini Cooper were available with a ZF VT1F continuously variable transmission or with a conventional Midlands (Rover R65) 5-speed manual transmission (model years 2002–2004); the latter was replaced with a Getrag 52BG 5-speed unit for the remainder of the Mk I production (2005–2006). The Cooper S came with a 6-speed Getrag G285 manual or an Aisin 6F21WA/TF60SN fully automatic transmission with paddle shifters. The gear ratios of the 6-speed Getrag manual transmission were changed from July 2004 production and onwards.

All Minis had a drive by wire electronic throttle, anti-lock brake electronic brakeforce distribution, and BMW Cornering Brake Control. Stability options were BMW's ASC traction control system and DSC electronic stability control, to improve control and handling in adverse conditions.

The addition of a supercharger to the Mk I Cooper S required that the battery be relocated into the rear of the car – leaving no room for a spare tyre, so the S models came with run-flat tyres.