Agriculture Minister Lobin Low sent a letter to Tyson inviting him to take up the role, and said legalisation in Malawi had created new opportunities.
Tyson, a former world heavyweight champion, is an entrepreneur and has invested in a cannabis farm in the US.
But the move has been criticised by some as the former boxer was imprisoned for sex offences in the 1990s.
“Malawi may not go it alone as the industry is complex [and requires] collaboration. I would therefore like to appoint you, Mr Mike Tyson, as Malawi’s Cannabis Branch ambassador,” Mr Lowe wrote.
The United States Cannabis Association was facilitating the deal with Tyson, the agriculture ministry said.
“Tyson will be working with us,” she said.
Malawi legalised the growing and processing of cannabis for medicinal use last year, but stopped short of legalising it for personal use.
The country’s agriculture ministry has encouraged farmers to grow cannabis for medicinal purposes as well as hemp for industrial use.
The government hopes Mr Tyson’s backing will “rope in some investors and even potential buyers”, ministry spokesman Gracian Lungu told the AFP news agency.
A locally grown variety of cannabis – Malawi gold – is renowned by recreational users across the world.
The Centre for Public Accountability, a Malawian civil society group, criticised the latest move due to Tyson’s previous crimes.
The former boxer was jailed in 1992 after being convicted of rape in Indiana. He was released in 1995 after serving less than three years of his sentence.
“The CPA is failing to comprehend why Malawi would want to have a convicted rapist as its brand ambassador, more especially, at this time, when efforts to curb violence against women are part of the government agenda,” the group’s acting director, Kondwani Munthali, said in a statement.