Mighty first went missing last week.
In a tribute post to his departed pet, who Bloom welcomed into his family in 2017, the Lord of the Rings star revealed that he got a tattoo in honor of the late pup. Bloom opted to get an ace of spades inside a heart inked under Mighty's name on his chest.
"Mighty’s on the other side now. After seven days of searching from sunrise to sunset and into the wee hours, today, the 7th day ~the number of completion~ we found his collar," Bloom began the caption. "I have wept more this week than I thought possible, which has been very cathartic and healing."
Bloom wrote that he "left no stone unturned" in the search for Mighty, which included him crawling "thru all the man holes, under the roads, [searching] every back yard and creek bed," as well as having "two separate sniffer dogs" deployed.
"I feel so grateful to have learned from my little Mighty man that love is eternal and the true meaning of devotion," Bloom wrote. "I feel sure he was looking down on me whistling in every back yard and knowing that I was doing all I possibly could to respect our bond. He was more than a companion. It was a soul connection for sure."
"I’m sorry. I love you," he continued. "Thank you. RIP my MIGHTY HEART my little fellow A ♠️’s."
Bloom concluded his post by thanking his community for its support, which allowed him to "see the best of people even in the worst of times." Additionally, he expressed his gratitude for Dog Days Search & Rescue, noting that the people there are "heaven sent." Lastly, Bloom thanked his tattoo artist, Scott Campbell, for inking him, writing, "I love you brother."
Bloom's celebrity pals took to the comments section to express their grief at the news, with his fiancee, Katy Perry, simply writing, "I love you."
"The tears won't stop," Jennifer Aniston commented. "I'm so so so deeply sorry my friend. I love you."
"My heart hurts for you, my man," Glen Powell wrote.
Meanwhile, Cynthia Erivo expressed that she was "gutted" by the news, while Luke Evans wrote "I'm sorry buddy."
During the search for Mighty, Bloom took to Instagram to share his love for his dog and his hope that the pup would be found.
"I don’t recall a time in my life where I’ve been so broken wide open," Bloom captioned a slideshow of pics of himself with Mighty. "The rawness I have felt over these past few days and sleepless nights at the idea of my little man being lost and scared, with me unable to do anything to protect him, is a waking nightmare."
"... The bond between Mighty and I shows devotion in ways I have not truly understood until now. I am a devoted father & partner, still, there is a reason why they call them ‘man’s best friend,'" he added. "I miss him. Send out a prayer for my little strong and Mighty boy to find his way back to his family. ?❤️."
In a 2017 interview with Nick Grimshaw on BBC Radio 1, Bloom recalled how his son, 9-year-old Flynn, was to thank for welcoming Mighty into the family.
"My son wanted a very small dog, and this one magicked its way into his life. I didn't pick it. I didn't choose it. I wouldn't necessarily have, but he did, in many ways, because he was like, 'I want a mini dog,' and then there was a mini dog," he explained. "It's a teeny, tiny dog. When I first got it, it was the size of this cup of tea. It was tiny, teeny, and I was worried its was going to... but now he's got a bit more about him. He's about the size of my shoe -- two shoes. He's about a pound a half."
"I'm obsessed. I've started to Instagram -- I just do stories of the dog the whole time," Bloom added, joking, "I think it roughens my masculine edges."