The Northern line ticket hall at Elephant & Castle station reopened on Friday after the completion of a major refurbishment programme.
The hall has been expanded and modernised and the two lifts at the station have been completely refurbished with additional entry and exit gates.
Customers have been able to use the station throughout these works as the Bakerloo line ticket hall has remained open and both Northern and Bakerloo line trains have continued to serve the station.
Work on the hall commenced in February 2001.
Bakerloo line general manager Penny Hazell said: "This is excellent news for those who live and work around Elephant & Castle. Not only will customers have new improved facilities but this will also contribute to the regeneration of the Elephant & Castle area.
"These works have taken longer than originally planned and we would like apologise to customers for the inconvenience this has caused but they will now have the use of a more spacious ticket hall with greatly improved facilities."