Ensign entered Formula One in 1973, funded by pay driver Rikky von Opel, who had previously driven for the team in Formula Three and won the British Formula Three Championship in 1972. The first Formula One season yielded little success; von Opel completed only two races, with the team's best result a 13th place at the British Grand Prix. The partnership continued into 1974 but von Opel departed after the opening race, having secured a works Brabham drive. Vern Schuppan replaced him and recorded a 15th place in Belgium before being succeeded by Mike Wilds, who qualified only at the United States Grand Prix.
For 1975, principal sponsorship came from Dutch company HB Bewaking, and the team signed Dutch drivers Roelof Wunderink and Gijs van Lennep. Wunderink had limited success, qualifying for three races and finishing one. Van Lennep qualified consistently and scored Ensign's first World Championship point by finishing sixth at the German Grand Prix. Chris Amon also raced for the team at two rounds.
In 1976 Amon remained and produced strong qualifying performances, reaching third on the grid in Sweden and sixth in Britain, but scored points only in Spain with a fifth place. For 1977, Clay Regazzoni joined Ensign and delivered five points with best finishes of fifth in Italy and at the United States Grand Prix.
The 1978 season saw Danny Ongais and Lamberto Leoni start the year, but both departed early. Jacky Ickx contested four rounds and Derek Daly raced the remainder, scoring a point in Canada. Nelson Piquet made his Formula One debut at the 1978 German Grand Prix at Hockenheim in an Ensign. Daly continued with the team in 1979 but left after Monaco; Patrick Gaillard replaced him and qualified in only two of five attempts before Marc Surer took over for the final three races.
A serious accident marked the 1980 season. Clay Regazzoni returned to Ensign but at Long Beach his brake pedal failed at the Queen's Hairpin, and his uncontrolled car struck the parked machine of Ricardo Zunino, leaving Regazzoni paralyzed. Tiff Needell raced in Belgium but failed to qualify at Monaco, and Jan Lammers completed the season.
Marc Surer delivered Ensign's finest championship result at the 1981 Brazilian Grand Prix, finishing fourth in wet conditions and also recording the race's fastest lap. He added a sixth at Monaco. From Spain onward, Eliseo Salazar took over and scored a sixth in the Netherlands. That year the team relocated from Chasetown to premises on Trent Valley Road in Lichfield.
Roberto Guerrero drove for Ensign in 1982, completing only two races. After the 1982 season, Ensign was merged with the Theodore team — which had existing financial links to Ensign through investor Teddy Yip — and the combined entity raced under the Theodore name in 1983 before folding during that year.
After Ensign's closure, Morris Nunn built a separate career in American single-seater racing. He served as a prominent chief engineer in the Champ Car series, winning championships with Alex Zanardi and Juan Pablo Montoya during the late 1990s.