Rowland was recruited to the London and Rhodesian Mining and Land Company, later Lonrho, as chief executive in 1962. Under his leadership, the firm expanded out of its origins in mining and became a conglomerate, dealing in newspapers, hotels, distribution, and textiles, and many other lines of business. During 1973, Rowland's position was the subject of a High Court case in which eight Lonrho directors sought Rowland's dismissal due to both his temperament and to claims he had concealed financial information from the board. Rowland failed in his legal attempt to block the move but was subsequently backed by shareholders and retained his position. British Prime Minister, Edward Heath, referring to the case, criticised the company in the House of Commons and described events there as "the unpleasant and unacceptable face of capitalism".
In 1983, Rowland took over The Observer newspaper and became its chairman. He also campaigned to gain control of Harrods department store in Knightsbridge, London but was defeated by the Egyptian-born tycoon Mohamed Al-Fayed
- Tom Bower Tiny Rowland: A Rebel Tycoon, London: Heinemann, 1993.
- Tiny in name, not in nature BBC Online, 26 July 1998
- Andrew Goodrick-Clarke Lonrho chief deceived board and concealed information, court told, The Times, 9 May 1973
- Andrew Goodrick-Clarke Lonrho chief fails in court, but shareholders will decide his future, The Times, 15 May 1973
- Andrew Wilson Huge Lonrho vote gives Mr Rowland sweeping victory and eight opponents are dismissed, The Times, 1 June 1973
- Mr Heath calls Lonrho affair 'the unpleasant and unacceptable face of capitalism', The Times, 15 May 1973
- Kim Sengupta Police were right to suspect Fayed of theft, rules judge, The Independent, 14 August 2002