Is it bad or unprofessional to ask for a raise?

Asking for a raise is a normal part of working life, and most managers expect it. What makes a request land badly isn't the asking, it's the framing: an ultimatum, a surprise in the middle of another meeting, a comparison with a coworker's pay, or a number with no reasoning behind it.

What makes a request land well

A dedicated meeting, requested in advance
Two or three results your manager can verify
One specific number based on the market range and your scope
A calm close: a decision, or criteria and a date

What makes managers uncomfortable

"If I don't get this, I'll leave"
"[Coworker] earns more than me"
"My rent went up"
Bringing it up at the end of an unrelated meeting

If you're nervous

Write your opening sentence and read it out loud a few times. Most of the discomfort comes from improvising, not from the request itself.

Questions

Will my manager think I'm ungrateful?

Not if you tie the request to the work and keep the tone warm. Recognition and compensation are separate topics, and it's fair to discuss both.

Can asking for a raise hurt my career?

A well-prepared request rarely does. If you're worried about retaliation, the rules vary by country and state, so speak with a qualified employment lawyer.