Mr Hills, Ms Irving and Richard Stebbing, of Auckland University, were selected as Rhodes scholars at a meeting at Government House in Auckland this week.
Otago students are continuing a winning streak by having gained two of New Zealand's three annual Rhodes Scholarships.
They have for the last two years.
Mr Hills (24) was born in New Plymouth and has just completed his MB ChB studies at the university's Wellington School of Medicine.
His Rhodes success was a "huge honour" and also reflected positively on the high quality education he had received at Otago University and its Faculty of Medicine, he said.
"My decision to head south to study at Otago was one of the best I've ever made," he said.
Mr Hills will return to New Plymouth next week, taking up a house surgeon post at Taranaki Base Hospital.
At Oxford, he intends studying for an MSc in integrated immunology leading to his eventual goal, a DPhil programme.
After his studies, he plans to return to New Zealand to train as a specialist.
He has taken part in Otago University's rural medical immersion programme and this year took up a medical elective in Zambia.
Ms Irving has undertaken study for an LLB (Hons) and BA in community and family studies and expects to complete her Otago academic work midway through next year.
At Oxford, she will study for a bachelor of civil law degree and an MSc in criminology and criminal justice.
She intends to work as a criminal defence lawyer, then in social policy and legal reform work.
Born in Hastings, she attended Havelock North High School.
She has served as a volunteer at law centres and as a Pacific Island mentor and tutor at the Otago Faculty of Law.
A runner-up in the New Zealand Law Students Association Mooting Nationals, she is Otago University's mooting champion and has won several university law prizes.
• Earlier this year, Otago students also gained two of the three national Rutherford Foundation Scholarships to support study at Cambridge University next year.
