Riverside ward councillor Anood Al-Samerai has officially opened the latest facilities at the Whites Grounds Skate Park off Crucifix Lane.
The skate park, which occupies a railway arch, was opened three years ago.
The improvements were funded by section 106 contributions intended to mitigate the impact of major local developments.
"One of the things that people always ask for is better youth facilities," said Cllr Anood Al-Samerari, Riverside ward councillor and Southwark Lib Dem leader.
"This is a great example of what we can do when we work together and use the money locally on local facilities."
Forge has also produced plans for a possible third phase of development which would see a new youth centre created in an adjacent railway arch.