McKesson provides health information technology services, medical supplies, and other healthcare management tools. The company is based in Irving, Texas and was originally founded in 1833 as Olcott and McKesson by John McKesson and Charles Olcott. The company also specializes in technologies like bar-code scanners, pharmacy robotics, and RFID tags.

Since the 20th century, the company has increasingly invested in medical technology with the acquisition of various other medical information systems firms like HBO and Company in 1999. This trend continued into the 21st century as well when McKesson acquired US Oncology, a leading provider of cancer services for $2.16 billion and integrated it into the McKesson Speciality Health Business. The pharmaceutical giant also diversified into other areas when the information technology wing of McKesson and McKesson Technology Solutions was created in 2001. McKesson Technology Solutions has also acquired its own acquisitions, including some notable ones like Per Se Technologies, RelayHealth and Practice Partners.

Continuing this trend of acquisitions, the company made its biggest acquisition yet when it acquired Celesio, a German healthcare and pharmaceutical company in 2014 and registered annual revenue of more than $179 billion.

Besides the USA, McKesson has branch offices located in other parts of the world including in countries like Australia, Ireland, France, the Netherlands, and the UK. In 2019, the company recently shifted its headquarters to Irving, Texas.