Kyari worked for the law firm Fani-Kayode and Sowemimo for some time after his return to Nigeria.
From 1988 to 1990, he was Editor with the New Africa Holdings Limited Kaduna.
In 1990, he served as a Commissioner for Forestry and Animal Resources in Borno State.
From 1990 to 1995, Kyari was the secretary to the board of African International Bank Limited, a subsidiary of Bank of Credit and Commerce International.
Kyari was an executive director in charge of management services at the United Bank for Africa, and was later appointed the chief executive officer. In 2002, he was appointed a board director of Unilever Nigeria, and later served on the board of Exxon Mobil Nigeria.
In August 2015, Kyari was appointed Chief of Staff to President Muhammadu Buhari.
Since his appointment, Kyari has become an influential figure within the Buhari administration.During the administration’s first term, he worked mainly behind the scenes to implement the president’s agenda. In 2019 with Buhari’s re-election for a second term, he ordered his cabinet to channel all requests through Kyari’s office.
Further enhancing his influence within government circles, and being labelled as the de facto head of government.
In 2017, following a leaked memo, Kyari became embroiled in a public argument with the Head of Civil Service who was later removed from office and arrested. In 2020, in another leaked memo, Babagana Monguno the National Security Adviser accused Kyari of meddling in matters of national security.