More than a fifth of undergraduates who secured places at Oxford University last year were from black and minority ethnic (BAME) backgrounds.
The university said the 22.1% of new students coming from a BAME background in 2019 was up from 18.3% in 2018.
Its vice-chancellor Prof Louise Richardson said the figures showed "steady progress towards diversifying the make-up of our student body".
But some colleges and courses remain much more diverse than others.
The university's Annual Admissions Statistical Report showed five or fewer black UK students were admitted to 13 of Oxford's largest courses between 2017 and 2019.
One UK black student won a place to study biology and two were admitted to study history and politics. None earned a place to study geography.
The university said it will expand online resources to increase diversity. Its state school access programme, UNIQ, will run exclusively online this year, as will the Target Oxbridge scheme, which helps black students with applications.
Prof Richardson said: "The impact of the Covid-19 pandemic has exposed the deep education inequalities in our society. We are acutely conscious of its differential impact both on our current students and on those considering applying to Oxford."
The proportion of British state school pupils winning a place at Oxford increased to 62.3%.
But the chance of a state school pupil being successful varied significantly between colleges. Of Mansfield College's undergraduates arriving between 2017 and 2019, 94% went to state schools. Conversely, 50.2% of Christ Church College's undergraduates over that period went to state schools.
The university had planned to publish its report earlier this month but it was postponed after the death of George Floyd sparked protests around the world, including at Oriel College, Oxford.
The college said last week that it will take its statue of imperialist Cecil Rhodes down after Black Lives Matter protests.