Heidi shared the happy news Monday on her Instagram and Twitter page, gushing about getting engaged to her man after a little over a year of dating.

Heidi posted this cute black and white photo with the caption, "I SAID YES."

It looks like Heidi can't wait to get married to Tom ... she's got her left hand draped all over her man and they're both beaming as they flash the engagement ring.

The German super couple -- Tom's the guitarist for Tokio Hotel -- shared the news the day after a fun, family trip to Disneyland.

Heidi has gotten hitched twice before. She was married to Ric Pipino from 1997 to 2002 and Seal from 2005 to 2014.