Actelion was founded in 1997 by a small group of researchers and managers from Roche. CEO Jean-Paul Clozel and the other founding members built the company’s legacy on ground-breaking innovation and an unwavering commitment to patients. Actelion fundamentally changed the way pulmonary arterial hypertension is treated and became a recognized global leader in this space. The company  also has a number of specialty therapies and compounds in late-stage development for pulmonary hypertension, multiple sclerosis and infectious diseases.

Actelion went public in April 2000, with registered shares listed on the SWX New Market. During its 20-year history, Actelion grew to more than 2,600 employees in over 30 affiliates, reaching more than 50 markets with its medicines.

In January 2017, Johnson & Johnson (J&J) and Actelion announced a definitive transaction agreement under which J&J would acquire Actelion.

In June 2017, the acquisition was completed and Actelion became part of the Janssen Pharmaceutical Companies of Johnson and Johnson. Actelion's medicines help expand and strengthen Janssen’s portfolio with leading, differentiated in-market medicines and promising late-stage compounds. Janssen has added Pulmonary Hypertension as a therapeutic area of focus to maintain the leadership position Actelion has built in this important disease area.

On 16 June 2017, Actelion applied for the de-listing of Actelion shares to the SIX Swiss exchange.