Hill & Knowlton is an American global public relations consulting company, headquartered in New York City.

[4] Hill served as chairman and chief executive until 1962, but remained on the firm's policy committee, and continued to go into the office until shortly before his death in 1977.

[5][15] In 1989, Hill & Knowlton acquired Canada's largest PR agency, the Public Affairs Resource Group.

[26][27] In January 2011, Hill & Knowlton announced a merger with Public Strategies, another WPP company founded in Austin, Texas in 1988.

The new services were part of Hill & Knowlton's support for the COP15 (UN Biodiversity) conference, which was held in Kunming, China, in October 2021.

[42] In March 2023, WPP acquired Germany based healthcare public relations agency 3K Agentur für Kommunikation.

In the same month, Hill & Knowlton also announced its partnership with Pendulum Intelligence to produce a tool that will help clients combat disinformation.

[15][52] In the 1970's, Hill & Knowlton representatives were present in a meeting with the Public Relations Subcommittee of John-Manville's Environmental Health Task Force.

[55] Also during the late 1980s, Hill & Knowlton represented the Bank of Credit and Commerce International (BCCI) during its money laundering scandal.

[5][57][58] Hill & Knowlton were later accused of spreading false information to increase support for the Gulf War, which the company denied.

[60][61] The Church of Scientology sued the firm, claiming that their contract was terminated because Hill & Knowlton was pressured to do so by Eli Lilly and Company, a client of JWT.

In November 2022, the company, as official PR firm for the COP27 climate summit in Egypt, was criticized by scientists and environmentalists for having an apparent conflict of interest - also working for fossil fuel corporations.