Luke Durbin, 19, of Hollesley, failed to return home after a night out in Ipswich on 11 May 2006.
No-one has been charged in connection with the case and the reward is the first to be put up since the investigation began.
His mother, Nicki, said: "My family and I desperately need answers."
Luke had spent part of the Thursday evening in Zest nightclub on Princes Street and was last seen on CCTV cameras near the Cattle Market bus station in the early hours of the following morning.
The reward has been put up jointly by Nicki Durbin, Crimestoppers, Suffolk Police, the East Anglian Daily Times and Ipswich Star.
Ms Durbin said: "It's more than nine years since I reported Luke as missing.
"We still believe somebody locally knows what happened to Luke and we're hopeful this reward can be the incentive that finally makes them come forward with the information that helps us find my son."
Det Supt John Brocklebank said: "We don't make decisions to offer rewards lightly because there are legal ramifications.
"We had enough lines of inquiry to pursue without offering a reward earlier and the timing is for operational reasons - we are now appealing for people who may have information who want or need the financial reward."
Suffolk Police said they also wanted to establish who was driving a white or silver Volvo 440 on Orwell Place at 04:09 BST on Friday, 12 May, 2006.
CCTV cameras captured a picture of the vehicle, but its number plate was not visible.
Police said they had confirmed there was a Volvo 440 in the Ipswich area with a M206 LYE number plate at the time, but it was registered under a false name and address and they are keen to hear from anyone who recognises this number plate so they can confirm whether it was the car in the CCTV images.
A reward of £20,000 has been offered in the case of a 19-year-old man feared murdered after he disappeared in Suffolk nine years ago.