Russell Wilson Mourns His Dog's Death, 'Heaven Got A Good One'

Sad news from Russell Wilson ... his beloved dog has died.

The Pittsburgh Steelers quarterback announced the heartbreaking update on his Instagram page just minutes ago ... revealing his Great Dane, Prince, passed away on Friday morning.

"I got you my rookie year," Russ said in an emotional note to his late pup, "& you have been a blessing to our family with so many memories, hugs, and kisses from our 4 kids and us."

"You will forever be a part of us. Today was a hard day."

Wilson shared that Prince battled cancer twice in his life ... but somehow overcame it -- and lived all the way to 12 years old.

"Heaven got a good one!" said Wilson, who shares two other Great Danes with his wife, Ciara. "Forever the Prince of Peace. Love you."

Fans of the former Super Bowl champion shared their condolences in the comment section of his post ... with one saying, "It hits so much harder when it's the pup who was there from the start. I feel for you so much."