The former couple, who revealed in April they were splitting up after nine years of marriage, shared touching individual tributes to the late canine, a pit bull Catahoula mix.
Dewan, 38, shared a sweet gallery of photos of herself and her and Tatum's 5-year-old daughter, Everly, snuggling up to Lulu. In her emotional caption, she revealed Lulu died of cancer.
"To our sweet and fierce Lulu ... thank you for being the best dog in the entire world and for fighting cancer for as long as you did. Thank you for your tireless love, protection and humor. Thank you for the adventures," she wrote.
"Heartbroken doesn’t even come close to how it feels. But you will live on forever in our hearts and our memories ... fly sweet angel," she added.
The batch of special memories includes an adorable video of Lulu enthusiastically licking Dewan's face. "Too much??" the "World of Dance" host wrote.
Tatum, 38, shared a black-and-white photo of Lulu running alongside him on a shore.
"I’ll see you again baby girl. But you’ll always be with me. Always," he wrote, adding special thanks to the photographer for the happy "memory."
The "Magic Mike" star shared more photos of Lulu in his Instagram story, including one where Lulu nuzzles up to her master as he lies on a sandy beach.
"They have every treat, every bone,” Dewan explained, adding that it was like the pooches had "won the lottery."
While Meeka loves accompanying Dewan to the spa, Lulu's more adventurous personality made it easy for her to bond with Tatum.
“Lulu is like a fur Chan,” Dewan explained. “They are the same person. She’s wild, she loves adventure, she’s always like, ‘Where are we going? What are we doing?’ She’s a big baby, but she’s kind of vicious and also just ready to go all the time.”