"My #WCW my #beautifulblackqueen…My life mistakes gave me you and my life mistakes almost made me lose you," he wrote as a caption to the photo of the actress.
"But your love has conquered all and I hope to spend the rest of my life with you…"
The last several months have been a whirlwind for the famous couple.
The two revealed that they were engaged shortly before Christmas, just days after the Miami Heat star announced that he fathered a son outside of his relationship with Union during a press conference on Monday, Dec. 30.
"I had a time, a part in our break, in our pain and our hurt, a blessing came out of it in my life, having a son that was born healthy," the 31-year-old told reporters. "So I'm moving on."
The press conference took place just before the Heat played against the Denver Nuggets at the Pepsi Center, merely hours after Wade's baby news hit the Internet.
"I'm in the public eye, so obviously that's a part of it," Wade said of his son's birth making headlines. "It comes with the territory."