Ecolab Inc., headquartered in St. Paul, Minnesota, is an American global provider of water, hygiene and energy technologies and services to the food, energy, healthcare, industrial and hospitality markets. It was founded as Economics Laboratory in 1923 by Merritt J. Osborn, and renamed "Ecolab" in 1986.

Merritt J. "M.J." Osborn founded Economics Laboratory in 1923 with the tagline "Saving time, lightening labor and reducing costs to those we serve." The company's original product was Absorbit, a product designed to quickly clean carpets in hotel rooms. This was soon followed by Soilax, a dishwasher soap. During the 1930s, the company expanded throughout the United States and sales reached US$5.4 million by the end of 1940s. It acquired the Magnus Company in the early 1950s, which gave the company access to Magnus's industrial specialty businesses - including pulp and paper, metalworking, transportation, and petrochemical processing.

In the 1950s, international expansion of Economics Laboratory started, with the establishment of its first overseas subsidiary in Sweden in 1956. It became a publicly traded corporation in 1957, and continued to expand during the 1960s and 1970s. In 1979, it acquired Apollo Technologies, but in 1983 the acquired Apollo subsidiary was shut down.

In 1986 the company changed its name from Economics Laboratory to Ecolab Inc.

In 1987, Ecolab purchased the lawncare servicer provider ChemLawn for US$376 million. It sold the acquisition in 1992 to ServiceMaster for US$103 million as it couldn't turn ChemLawn into a profitable business. Ecolab and the German fast-moving consumer goods firm Henkel KGaA formed a 50:50 European joint venture called 'Henkel-Ecolab' in mid-1991 to expand into European/Russian markets.

Ecolab would continue to acquire companies in the 1990s, namely Kay Chemical (1993), Australia-based Gibson Chemical Industries Ltd (1997), and GCS Service Inc (1998). In 2001 it bought out its partner Henkel's 50% stake in the European joint venture, Henkel-Ecolab. Ecolab integrated the former Henkel-Ecolab into its existing global operations. As a legacy of the Henkel-Ecolab cooperation from 1991–2001, Henkel continued to hold a 29.5% stake in Ecolab Inc. after the sale of the joint venture.

In the mid-2000s, strategic acquisitions continued, and Ecolab diversified its portfolio of customer offerings by venturing into the food safety management business as well as a healthcare business unit. In 2005, it opened a new global research, development, and engineering center in Eagan, Minnesota.

In 2008, Henkel sold all of the 73 million shares, i.e., nearly a 29.5% stake it held in Ecolab, ending the two-decade-long partnership. The same year, Ecolab established Zurich as its Europe, the Middle East and Africa headquarters.

In 2010, Ecolab was ranked #365 in Fortune 500 magazine, and in 2011 Ecolab was named one of the "World's Most Ethical Companies" by the Ethisphere Institute.

In July 2011, Ecolab announced a merger with Nalco Holding Company, Inc., and in December 2011 Nalco became a wholly owned subsidiary of Ecolab Inc. after it completed its US$5.4 billion acquisition.

In May 2012, Microsoft co-founder Bill Gates, through his investment vehicles—Cascade Investment and the Bill & Melinda Gates Foundation—increased his stake of 10.8% in Ecolab to 25%.

In October 2012, Ecolab entered an agreement to acquire Champion Technologies. That purchase closed in April 2013.

In November 2015, for $40.5 million Ecolab acquired the U.S. operations of Charlotte, N.C.-based Swisher Hygiene which provides hygiene and sanitizing solutions for the foodservice, hospitality, retail and healthcare markets.

In July 2016, Ecolab made a minority equity investment in Aquatech International, LLC of an undisclosed amount.

Ecolab employs approximately 47,000 people, and operates in more than 170 countries. It is organized in the following geographical divisions:

Ecolab provides water, hygiene and energy technologies and services to the food, energy, healthcare, industrial and hospitality markets.

The company's food safety services provide consulting to restaurants, hospitals, food retailers and food & beverage manufacturing facilities. It is also a supplier of chemicals used by beef and poultry processors - to reduce pathogens, such as E. coli and salmonella - in uncooked beef and poultry.