Joseph Shade, 24, who played Ian Beale’s son Peter between 1998 and 2004, admitted sending sexual text messages to the three girls and touching one on the bottom.
Prosecutors said he sent pictures of himself via Snapchat and requested topless photos through Facebook.
Shade, from Sheringham in Norfolk, was working at a youth project in the county when the offences took place between 2012 and 2015.
The vulnerable girls were between 14 and 17, and he was between 19 and 21 at the time.
Shade initially sought help from the youth project as a young person, but became formally employed as a youth worker after turning 18.
The judge said he had been in a “position of trust”, but that she was taking his age at the time into account.
Shade admitted to police that he had taken advantage of his position but “he said he saw himself as a young person and not as a staff member”.
His defence lawyer described his role as a youth worker as “plainly quite beyond him.”
Shade originally denied 11 sexual offences against four girls, but on the fourth day of the trial he admitted six offences against three girls.
Prosecutors said the remaining five counts will be kept on file.
Shade has been barred him from working with children and vulnerable adults for five years and must complete 150 hours of unpaid work and sign the Sex Offenders Register.
© 2017, Vale of Glamorgan Broadcasting CIC T/A: Bro Radio & Sky News.