The Conservative donor and ex-business partner of MP Jacob Rees-Mogg was given a lifetime peerage so he could serve in Liz Truss’s government, but was later dismissed by Mr Sunak.
The Department for International Trade has been approached for a comment.
Ministers are expected to declare their financial interests within a month of being appointed.
Last month, opposition politicians complained that Lord Johnson of Lainston had failed to publish his interests in India ahead of an official visit to the country.
Speaking in the House of Lords, he later explained he had an “equity in a fund management business that invests in India”.
Labour’s former shadow international trade secretary Emily Thornberry, who is now shadow Attorney General, tweeted: "Surely this isn’t true. Dominic Johnson has now been reappointed by Rishi Sunak as a trade minister?
“The same Dominic Johnson who was sacked from the role a month ago, and then told British farmers they should convert their farms into offices? Please tell me this is a joke.”
Earlier this month, Lord Johnson told Politico the government should be honest with farmers about how trade deals might damage their business and could be helped to transition their buildings into offices.
Before getting involved in politics, Lord Johnson set up investment firm Somerset Capital with former Business Secretary Jacob Rees-Mogg.
Since 2014, he has donated more than £250,000 to the Conservatives and from 2016 to 2019 worked as the party’s vice-chairman.
Following his initial appointment as a trade minister by Ms Truss, Labour described him as an “unelected asset fund manager” and “crony party donor”.
Out one door and another … it’s a party game … 
