Donald Trump Jr. and Bettina Anderson Are Officially Married

Donald Trump Jr. and Bettina Anderson are officially official ... because the couple quietly was wed ahead of their lavish Bahamas wedding weekend.

According to the marriage certificate, obtained by TMZ, Don Jr. and Bettina checked the legal box Thursday, with a Palm Beach County deputy clerk signing off on the license ... paving the way for the couple’s upcoming "I do" moment on a private island in the Bahamas.

The ceremony was officiated by Brad McPherson ... a longtime real estate attorney who has worked closely with the Trump family for years. This was a legal formality the pair needed to handle before their actual ceremony outside of the U.S.

BTW, it looks like Bettina's not legally taking the Trump name ... according to the certificate.

Don Jr. and Bettina plan to exchange vows in front of a small group of family members and close friends during an intimate celebration this weekend. One notable absence, though -- President Donald Trump has already said he will not be attending the wedding festivities.