Can an undergraduate attend a conference without a supervisor? I am an undergraduate student graduating next month. I have submitted my paper (my own paper) to a conference and it has been accepted. Is it okay to attend the conference and present without any supervisor since it is my own result?
The answer is "yes", in that I'm not aware of any conferences that have any rules prohibiting unaccompanied undergraduates (or, indeed, recent graduates - congratulations!).

With that said, depending on the conference in question you might get more out of it by talking to somebody from your university who is going and spending some time in their company. They might be able to introduce you to interesting people, you might learn by being in conversations with them, and they might be willing to provide context for what you hear. (but do remember that they are there primarily for their own reasons, not for your benefit!)