Diro was elected to the National Parliament of Papua New Guinea at the 1982 election, winning the Central Provincial seat.[4] He was briefly the Leader of the Opposition from 1982 to 1983.[6] He served as Minister for Forests under Paias Wingti from November 1985 to mid-1986, Minister for Foreign Affairs from 1986 to 1987 and Minister Without Portfolio from August to November 1987. He resigned from Cabinet in November 1987 over mounting controversy around alleged corruption while he was Minister for Forests and having received undeclared campaign funds from Leonardus Benjamin Moerdani, the head of the Republic of Indonesia Armed Forces. Despite the ongoing controversy, he returned to Cabinet from April to July 1988 as Minister for State in the last months of the Wingti government, before again returning in that role from May 1989 to April 1990 under Sir Rabbie Namaliu. He was Deputy Prime Minister under Namaliu from April 1990 to October 1991, when he was convicted by a leadership tribunal of 81 counts of official misconduct. The conviction sparked a constitutional crisis when Governor-General Sir Serei Eri, who had been president of Diro's party before assuming the role, purported to reinstate Diro; the resulting controversy saw both Diro and Eri resign.[7][3][8]
On 9 July 2018 Loop announced that Papua-New Guinea's first Guardian class patrol vessel would be named HMPNGS Ted Diro.[11] Australia had launched the vessel in June, and its sea trials were expected to finish by October. Delivery is scheduled for December 2018.[12] Diro was present when the vessel was commissioned, on 1 February 2019.[13]
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Miriam Zarriga (2018-10-22). "No talks on new base at Lombrum says Toropo". Post Courier. Retrieved 2018-10-23. Four Guardian class patrol boats will be gifted to PNG to replace the four with the first boat to be delivered in December and named after the first PNGDF Commander Retired Brigadier General Ted Diro.
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Michael Arnold (2019-02-05). "PNCFG vessel named after Diro". Fiji Post Courier. Retrieved 2019-02-05. Brig-Gen Diro, who was present for the commissioning of the HMPNGS Ted Diro last Friday, along with Major General Gilbert Toropo (current PNGDF commander) saluted the gesture in what both men described as another illustration of the enduring friendship between PNG and Australia.