Whats a polite way to turn down a job offer?

I would tell them that you would really like the job and thanks for the offer. However you are commited to your current employer and feel it would be unfair to let them down.

First, congratulations on being in the position you're in. Isn't it great when you like your job? =D I think there are already many great ideas in this thread. I am curious though. Why do you think you are about to be offered a job? Did you go on an interview? If you did not approach them for a job, then perhaps you can drops hints before they even offer you the job... to avoid the problem altogether. If you have the opportunity to mention your job to them, rave about it and say some of the things you said here. Express your enthusiasm and say something that makes it clear you hope to stay and grow at your current job.

Just tell them you really appreciate the offer and that you are sorry you have to turn it down. You already have a job that you enjoy and would like to stick with it. That's about it! If you want to say something similar in big words it'll be even better. They'll totally understand and really, it happens a lot so its no big deal.

Just tell them that you're already in a job you love and you don't want to give it up....

Just explain the facts. They'll understand and i'm sure they'll have no problem in finding someone else.

Everything that you just told us... tell them...nicely.