How do I get a credit card with a cosigner?

You can’t apply for a credit card with a cosigner. None of the top 10 credit card issuers allow cosigners on your application, though a few, like Bank of America, Capital One, and U.S. Bank, allow you to add a joint accountholder after you are approved for a credit card. Other alternatives to getting a cosigner include asking a family member to add you to their account as an ... read full answerauthorized user or applying for a secured credit card.

All major credit card companies allow authorized users, most with no minimum age requirement. Authorized users can get a card attached to the account in order to make purchases. They will also build credit if the primary accountholder pays the bills on time and doesn’t max out the credit limit. But authorized users aren’t legally responsible for any payments. Adding an authorized user is simple and can usually be done online.

The other alternative to getting a credit card cosigner is applying for a lower-level credit card. Secured cards provide the highest approval odds, and some don’t even check your credit history when you apply. This is only an option if you’re at least 18 years old and have a bit of income, though.

Co Signing for anyone (including your little sister) would be very poor financial decision and it could very negatively impact you. Here is what Bible has to say about those who cosign:
"One who lacks sense gives a pledge and puts up security in the presence of his neighbor."
Proverbs 17:18

As a general rule, co-signing is unwise and I usually advise against it.
It's not just a question of your ability to afford the payments, but rather if you want to be making them. I know it's kind of cold, but expect the worst and then ask yourself if you want to live with that.... read full answer
Hope that helps.

SecondHalfPlanning.com