Calatrava initiated his architectural studies at the Polytechnic University of Valencia, Spain, graduating in 1974. In 1975 he began a course in structural engineering at the Swiss Federal Institute of Technology (ETH) in Zürich, receiving a Ph.D. in 1979 for a thesis entitled On the Foldability of Frames. In 1981 he established his own architecture and engineering firm in Zürich. (He would later open offices in Paris and Valencia.)

Calatrava gained a reputation for his ability to blend advanced engineering solutions with dramatic visual statements, in both bridges and buildings. When Expo '92 was going to Sevilla, Spain, the city needed to have bridges constructed to allow access to an island that would be used for exhibitions. Calatrava's Alamillo Bridge (1987–92), built for this purpose, instantly received international attention. The dramatic structure's central feature is a 466-foot (142-metre) pylon that inclines asymmetrically away from the river, supporting a span with more than a dozen pairs of cables. The dramatic image, resembling a harp, transformed bridge engineering into a form of sculpture that can invigorate its surrounding landscape. Calatrava's other innovative bridges include the Lusitania Bridge (1988–91) in Mérida, Spain, and the Campo Volantin Footbridge (1990–97) in Bilbao, Spain.

In his architectural commissions, Calatrava used his knowledge of engineering to create innovative, sculptural structures, often in concrete and steel. He stated that nature served as his guide, inspiring him to create buildings that reflected natural shapes and rhythms. He was intensely interested in the architectural use of zoomorphic forms, a passion evident in such buildings as Turning Torso (1999–2005), his unique apartment tower in Malmö, Sweden. Its sculptural shape suggested a twisting spinal column. For the Lyon (France) Airport Railway Station (1989–94), he created a building that resembled a bird with outspread wings; the interior skeletal steel frame reinforced this birdlike effect. The bird allusion had symbolic meaning as well, since the station served as the end point of the route from Lyon to the airport. Calatrava's other memorable buildings include a renovation of the Stadelhofen Railway station (1983–90) in Zürich, the BCE Place Gallery and Heritage Square (1987–92) in Toronto, Tenerife Opera House (1991–2003) in the Canary Islands, and several structures (including an opera house, an arboretum, and a planetarium) for the City of Arts and Sciences (1991–2004) in Valencia.

Calatrava received the contract to design the new rail station on the former site of the World Trade Center in New York City in 2004, and the following year he was awarded the Gold Medal of the American Institute of Architects. In 2007 work began on his design for the world's tallest residential building, the Chicago Spire (2,000 feet 【610 metres】).