The 44-year-old reportedly popped the question to the controversial former Fox News host last year, entering 2021 as the future Mr. and Mrs. Trump Jr.
Daily Mail broke the story on Monday, posting photo evidence after their 2020 engagement. Somehow the duo has been keeping their wedding plans under wraps for a whole year, despite Donald Jr. giving Kimberly an almost 8-carat diamond ring.
"Don and Kim got engaged on New Year's Eve 2020 - which is Don's birthday. They've been together for almost four years now and have been friends for 15 years," a pal told the outlet.
"They've kept it private for the past year as they settled into life in Florida after moving from New York," the insider continued. "Both are focused on their children - they have six between them - and their work."
And while Trump, his son, and his future daughter-in-law have been holding onto this secret, their engagement is widely known among friends and family.
"It's been an open secret for the past 12 months with everyone Kim runs into admiring her almost 8 carat diamond engagement ring," the source added.
In a photo of the couple from Donald Jr.'s 44th birthday last month, Kimberly is seen sporting the attention-grabbing diamond — and being almost 10-carats, it's hard to miss in the snap.
She's not trying to hide it either.
Posting her ring-baring hand on her hip, the controversial news personality clung to her fiancé for the festive photo. Showing the oversized rock is square-shaped without a halo or any other diamonds around it, Donald Jr. went for classic chic when he shopped for the perfect sparkler.
Their engagement news comes just hours after it was revealed Donald Jr. has been subpoenaed as part of the New York Attorney General Office's ongoing civil investigation into his father.
He's not Trump's only child who has been called to testify either.
Ivanka Trump has also been subpoenaed as part of the investigation to determine if the former president inflated the value of some of his organization's assets.
The attorney general already subpoenaed Trump for testimony. The deadline is supposed to be January 7, but #45's legal team is attempting to crush his subpoena altogether.