The current rate of inmates taking their own lives at the Acklington jail was confirmed in data published by the Ministry of Justice.
Over the course of 2016, three people killed themselves at the male-only Category C unit, compared to one suicide in each of 2015, 2014 and 2013.
They were among a total of six people who died in custody at HMP Northumberland in 2016 – again another high over the last four years, with three deaths in 2013, five in 2014 and four in 2015.
A spokesman said that the jail works with the prisons and probation ombudsman and the police to investigate deaths at HMP Northumberland.
The figures show that an all-time record number of people (119) lost their lives through suicide in prisons in England and Wales last year, while people to die in custody (354 people) in 2016 was also a record high.