Originally released in its home market of Japan in late 1997 as the Toyota Harrier, export sales began in March 1998 as the Lexus RX.

Both front- and four-wheel drive configurations have been used on the RX series, and several gasoline powertrain options, including V6 engines and hybrid systems, have been offered.

By 1994, that vehicle was officially proposed by TMS executives at product planning meeting in Toyota City, Japan and put into development.

Prior to the RX public debut, a concept sport utility vehicle, the SLV, previewed the model at the Chicago Auto Show on 9 February 1997.

[13][14] The transmission, a 4-speed automatic unit, offered a "Snow" mode which started the vehicle in second gear for better traction in adverse weather conditions.

[17] The RX 300 interior featured leather trim, two rows of seating, and a rear cargo area which could be concealed beneath a tonneau cover.

[13] The center dashboard was dominated by a central liquid crystal display (LCD) multi-information screen for audio, climate, and performance data (including fuel economy),[13] along with a U-shaped wood trim piece and a pair of air conditioning vents.

Power and Associates in 1998,[25] Motor Trend Sport/Utility of the Year for 1999, Money magazine's Best Deal on the Road in the SUV class in 1999, and Kelley Blue Book's Best to Hold Value Award in 1999, 2000, and 2001.

[17] Its popularity contributed to the growth of the premium crossover SUV market, with several rival makes launching competing models in response to the RX 300.

[31][32] From the inside, the RX 330 interior featured genuine Golden Bird's Eye Maple or Walnut wood trim, a sliding multi-level center storage console, dual-zone climate control, and power tilt/telescopic steering column.

In Japan, the Toyota Harrier was the first worldwide production car with optional radar-assisted Pre-Collision System (PCS) (Forward collision warning only, no autonomous braking).

[38] The RX 330 (MCU33/MCU38) was powered by a 3.3-liter ULEV certified 3MZ-FE V6, rated at 230 horsepower (170 kW) SAE and 238 pound-feet (323 N⋅m) linked to a 5-speed automatic and was offered in either front or all-wheel drive.

All North American models were initially built in Japan until September 2003 when production of the RX 330 began in Cambridge, Ontario, Canada.

The RX 400h interior featured a hybrid information display on the navigation screen showing electrical motor, gasoline engine, and regenerative braking activation in real time.

However, the RX 400h did receive a facelift for the 2008 model year, featuring a blue Lexus badge and a rear spoiler that matches the body color.

The RX 400h gasoline engine switched off automatically and the car ran completely on electricity when either stationary, decelerating, or being driven at slow speeds—less than 60 km/h (40 mph).

Despite the increased performance, the RX 400h/Harrier Hybrid consumed roughly the same amount of gasoline as a compact four-cylinder sedan[49] and it qualified as a Super Ultra Low Emission Vehicle (SULEV) in the US.

In 2007 for the 2008 model year, the RX received a revised grille, chrome door handles, available new seven-spoke 18-inch alloy wheels with a liquid graphite finish, and Brandy Wine Mica or Desert Sage Metallic were new exterior choices.

Power also awarded the RX 400h the top spot for entry-luxury SUVs in its 2005 Automotive Performance, Execution and Layout Study on owners' attitudes towards new vehicle designs.

The first North American pre-production prototypes were sent to Cambridge, Canada in early 2008 for testing prior to the first RX 350 rolling off the production line on 28 November 2008.

[65][66][62] A hybrid concept vehicle, the LF-Xh, previewed the third-generation RX's design direction at international auto shows a year prior to the production model's debut.

[68] The RX 350 (GGL10/GGL15) features a revised 3.5-liter 2GR-FE V6 engine producing 275 horsepower (205 kW) with a wider power curve,[69][70] it remains ULEV-II certified and now uses a six-speed automatic transmission with sequential shift.

The new hard disk drive HDD-based navigation system no longer uses a touchscreen, instead replacing it with Lexus' Remote Touch controller, similar in function to a computer mouse, with haptic feedback.

[75] The powertrain is linked to an instrument panel Eco light indicator, which enables drivers to monitor their fuel efficiency as it correlates with accelerator modulation.

[75] In August 2010, Lexus began offering the RX 270 (AGL10), a front-wheel drive model with a 2.7-liter 1AR-FE inline-four engine, in Japan,[78] China,[79] and Russia.

[83] The facelift was unveiled at the March 2012 Geneva Motor Show with new wheels, interior colors, new head and tail lamps and new grilles.

[87][88] In 2014 (for the 2015 U.S. model year), the North American Lexus RX 350 gains new standard equipment such as the popular display audio package and LED front fog lamps.

The fourth generation of the RX was released in late 2015 and was presented at the 2015 Frankfurt Motor Show along with the new trim levels of the Lexus IS and GS.

[103] The AL20 features a redesigned 8.0-inch infotainment display that is now based on a horizontal axis; the dashboard is lowered to give the vehicle a spacious feeling.

Adjustments include optional parking sensors with blind-spot monitoring, rear cross-traffic alert, exterior automatically dimming mirrors, and an omnidirectional camera system.