The first generation Gemini was introduced as Isuzu Bellett Gemini in November 1974 as a 4-door Sedan and a 2-door Coupé with the same body shell as the third generation Opel Kadett (wheelbase 235 cm). The car was renamed Isuzu Gemini by November 1976. By 1975 it was assembled in Australia as Holden Gemini. In Malaysia it was known as Opel Gemini. By 1976 it was sold in the USA as Opel Isuzu, also known as Buick Opel. From 1981 on it was sold there as Isuzu I-Mark.

In May 1985 came the second generation Gemini with front-wheel drive and a wheelbase of 240 cm as a 4-door Sedan and a 3-door Hatchback. In USA it was sold as Isuzu I-Mark and Chevrolet Spectrum, renamed Geo Spectrum by the 1989 model year. In Canada it was known as Pontiac Sunburst.

The third generation Gemini was introduced in March 1990 as a 4-door Sedan only with a wheelbase of 245 cm. It was sold as Isuzu Stylus in the USA. By May, 1990 a 3-door Coupé with different body was introduced as Isuzu PA Nero, followed in September 1990 by the Gemini Coupé, accompanied in 1991 by a Coupé Wagon, called Gemini Hatchback.

From August 1993 on the fourth generation Gemini was a clone of the Honda Domani.

The fifth generation Gemini came in February, 1997 and is similar to the current Civic 4-door Sedan.