No, it must be the correct size and shape and have matching mounting bolts to fit the mounting holes on your toilet. You need to use a round toilet seat for a round toilet and an elongated one for an elongated toilet (unless using a specialized seat such as a plus-size seat).
There are a few American standard toilet bowl sizes (see above), and some toilet seats are designed to be compatible with all toilets. Specialized toilets such as bidets can have more bulk and must be measured thoroughly to make sure they fit snugly on your toilet.
The best thing to do is to be sure of your toilet's shape and measurements before you start shopping, so you can match it up to new toilet seat options.