Early Malay nationalism took root in Johor during the 1920s, he became a journalist and wrote articles on the welfare of the Malays. Some of Onn's articles were critical of Sultan Ibrahim's policies, which led to strained personal relations with the Sultan. In particular, Sultan Ibrahim expelled Onn from Johor in 1927 after he published an article in the "Sunday Mirror", a Singapore-based English tabloid, which criticised the Sultan's poor treatment of the Johor Military Forces personnel and the welfare of the Orang Asli. He went into exile in Singapore and became the editor of a Malay paper, "Warta Malaya", in 1930. Over the next six years, he edited four other newspapers including "Lembaga Malaya", "Warta Ahad" and "Lembaga". Onn became very popular after he continued to cover issues on Malay grievances, and Sultan Ibrahim invited Onn to return to Johor in 1936.