Justice Ruth Bader Ginsburg wrote a dissenting opinion on behalf of the liberal wing of the court.
"In a decision of startling breadth, the court holds that commercial enterprises, including corporations, along with partnerships and sole proprietorships, can opt out of any law ... they judge incompatible with their sincerely held religious beliefs," she wrote.
The justices ruled for the first time that for-profit companies can make claims under a 1993 federal law called the Religious Freedom Restoration Act (RFRA).
One of the two cases was brought by arts-and-crafts retailer Hobby Lobby Stores Ltd, which is owned and operated by David and Barbara Green and their children, who are evangelical Christians. The other case was brought by Norman and Elizabeth Hahn, Mennonites who own Conestoga Wood Specialties Corp in Pennsylvania.
None of the companies that have objected are publicly traded companies. Hobby Lobby has around 13,000 full-time employees while Conestoga Wood has 950.
The decision will affect similar cases brought by employers around the country. There are 49 cases in total, according to the Becket Fund for Religious Liberty. Religious institutions are already exempt from the requirement.
The company owners involved in litigation around the country do not all oppose every type of birth control. Some, including Hobby Lobby and Conestoga, object only to emergency contraceptive methods, such as Teva Pharmaceutical Industries Ltd's Plan B morning-after pill, and ella, made by the Watson Pharma unit of Actavis PLC.
Shares in drugmakers that sell popular forms of birth control, including Actavis and Teva, were little changed in morning trading after the ruling.
A Reuters/Ipsos opinion poll before the ruling found a majority of Americans oppose letting employers, based on their religious views, exclude certain contraceptives from workers’ insurance coverage.
The poll of 10,693 people asked whether employers should be able to choose what forms of contraceptives their health plans provide based on their religious beliefs. Of those responding, 53 percent disagreed and 35 percent agreed. Of those surveyed, 12 percent said they did not know.
The cases are Burwell v. Hobby Lobby and Conestoga Wood v. Burwell, U.S. Supreme Court, No. 13-354, 13-356.