The Wales midfielder has agreed terms on a deal until 2018.
Ramsey is currently recovering from a thigh injury but hopes to return soon to assist his side's Premier League challenge and bid for FA Cup glory.
The 23-year-old had scored 13 goals this season before his latest fitness setback and said: "I feel like there's plenty more to come. This season I've proven a lot of people wrong. There was a tough time in the period after my injury but I've got through that.
"Hopefully, now I can get back out on to that pitch soon, show what I'm capable of doing and, hopefully, finish off the season in some style."
Santi Cazorla and the promising teenage midfielder Gedion Zelalem have also signed new deals.