Zephaniah McLeod entered pleas at Birmingham Crown Court on Monday in connection with the spate of stabbings in the early hours of Sunday September 6 last year, as the city was packed with revellers.
McLeod, who appeared in court over a video link from Ashworth Hospital wearing a white T-shirt and dark blue zip-up top, spoke to confirm his name and say he understood proceedings, before entering pleas.
In addition to the charge of manslaughter, McLeod pleaded guilty to four counts of attempted murder and three charges of wounding with intent to cause grievous bodily harm.
The 28-year-old, of Nately Grove, Selly Oak, had been in custody since being charged with committing the attacks, which happened in the space of 90 minutes.
Jacob Billington, a Sheffield Hallam University graduate intern and drummer, was fatally stabbed in the neck, during the spree.
The 23-year-old, from Crosby, Merseyside, was among eight people stabbed during the attacks which triggered a major emergency services response.
His family were present in court and over the video-link to hear the pleas of McLeod, whom the court heard suffered with paranoid schizophrenia.
Seven others were injured in four clusters of attacks across the city centre, including Mr Billington’s old school friend and bandmate Michael Callaghan.
McLeod will be sentenced on September 27 and 28.