Theresa May said the appointment of Health Minister Jackie Doyle-Price to the new role will help tackle the stigma surrounding suicide.
While suicide rates are falling, 4,500 people take their own lives every year.
The appointment comes as ministers and officials from more than 50 countries assemble in London for the summit.
Wednesday’s meeting, hosted by Health Secretary Matt Hancock and attended by the Duke and Duchess of Cambridge, coincides with World Mental Health Day.
The government has also promised more support in schools, bringing in new mental health support teams and offering help in measuring students’ health, including their mental wellbeing.
Ms May said: “We can end the stigma that has forced too many to suffer in silence and prevent the tragedy of suicide taking too many lives.”
Alongside the announcement, the prime minister pledged £1.8m to the Samaritans so the charity can continue providing its free helpline for the next four years.