Ensign entered Formula One in 1973 with backing from Rikky von Opel, who had won the 1972 British Formula Three Championship for the team in an earlier, pre-F1 programme. The first season was not successful, with von Opel finishing only two races. The partnership continued into 1974, but von Opel left after the first race to join Brabham. He was replaced by Vern Schuppan and later by Mike Wilds.
In 1975, Ensign secured sponsorship from HB Bewaking, a Dutch company, leading to the signing of Dutch drivers Roelof Wunderink and Gijs van Lennep. Van Lennep scored the team's first championship point with a sixth-place finish in Germany. Chris Amon also raced for the team in Austria and Italy that year and stayed for 1976. Amon achieved strong qualifying results in 1976, including third on the grid in Sweden and sixth in Britain, and scored points with a fifth-place finish in Spain. Jacky Ickx raced for the team for the remainder of the 1976 season.
In 1977, Clay Regazzoni raced for Ensign, scoring five points with best finishes of fifth in Italy and America. Patrick Tambay also drove for Ensign in 1977, scoring points in three races. The team finished 10th in the World Championship with 10 points.
The 1978 season saw eight different drivers race for the team, including Danny Ongais, Lamberto Leoni, Jacky Ickx, and Derek Daly. Nelson Piquet made his Formula One debut driving an Ensign at the German Grand Prix at Hockenheimring that year. Daly scored the team's only point of 1978 with a sixth-place finish in Canada.
For 1979, Daly stayed with the team for the first part of the year before being replaced by Patrick Gaillard and then Marc Surer. The team struggled to qualify the car and scored no points.
The 1980 season saw Clay Regazzoni rejoin Ensign. At Long Beach, Regazzoni suffered a brake pedal failure, causing a crash that left him paralyzed. Tiff Needell and Jan Lammers also raced for the team that season but scored no points.
In 1981, Marc Surer achieved Ensign's best-ever result, finishing fourth at the Brazilian Grand Prix and recording the fastest lap of the race. Surer also finished sixth in Monaco. Eliseo Salazar replaced Surer from the Spanish Grand Prix onwards, finishing sixth in the Dutch Grand Prix.
In 1982, Roberto Guerrero raced for Ensign, finishing in two races. Outside the Formula One World Championship, the team won the British F1 Championship in 1982 with Jim Crawford driving the MN180B. At the end of 1982, Ensign merged into the Theodore Racing team, which had previous ties to financier Teddy Yip. Guerrero continued with the merged entity for 1983 before the Theodore F1 team shut down late in the year.
After Ensign's dissolution, Nunn moved into American open-wheel racing. He subsequently won CART championships with Alex Zanardi and Juan Pablo Montoya, establishing himself as one of the more successful constructors and team principals of his generation in the United States.