Darnell McCollins, 24, of Beck Square in Leyton, was on trial at Stafford Crown Court on June 3 last year when he approached two teenage girls.
He asked for their details, made repeat advances, and touched them both before they walked away and reported what had happened.
McCollins was arrested and questioned the following day but denied sexually assaulting the girls.
But when the case made it to court McCollins pleaded guilty.
On March 11 he was sentenced to 23 weeks in prison.
The sentence will run consecutively to a separate sentence he is serving.
Det Insp Emma Roach said: “I’m pleased that we were able to gather the evidence needed to convict McCollins of his crimes and to support the survivors as much as possible.
“We’re determined to deliver justice for victims of sexual crimes in Staffordshire and to act robustly against those responsible.”
He will be on the Sex Offenders Register for seven years and a restraining order was made regarding the victims.
