Mastiff Adoption in O Fallon, IL: Mastiff Puppies for Sale in O Fallon, IL

Adopt a Mastiff near you in O Fallon, Illinois

We don't see any Mastiffs available for adoption right now, but new adoptable pets are added every day. Try a different search below!

Or, how about these Mastiffs in cities near O Fallon, Illinois

These Mastiffs are available for adoption close to O Fallon, Illinois.

Red

Mastiff

Male, Adult

Swansea, IL

Size

(when grown) X-Large 101 lbs (46 kg) or more

Details

Good with dogs, House-trained, Spayed or Neutered, Shots are up-to-date,

Story

I received the dog in September 2025. I have papers on the dog showing birth, breed, neutered and current shot record. The dog is very timid, does not/will not sleep in a dog bed, and does not take getting shots well. Very good house dog and is house trained. Barks loud! I made my own schedule for taking the dog out daily to pee and poop. I take the dog outside 3 to 4 time daily. Dog does not run!

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Sweet Baby Ray

Mastiff

Male, 2 yrs

Belleville, IL

Size

(when grown) Large 61-100 lbs (28-45 kg)

Details

Spayed or Neutered,

Story

Sweet Baby Ray lives up to his saucy name in every possible way. He soaks up attention like it’s his life’s calling, greeting anyone who looks his way with a bright, eager spark. Food motivated to a heroic degree, he’ll happily showcase his best moves for a snack, and he keeps his space tidy like a little gentleman. His days are a blend of friendly greetings, playful bursts, and goofy antics that feel like tiny celebrations. He’s the kind of dog who turns ordinary moments into warm, waggy ones, always ready to charm his way into another cuddle or game.

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Hippie

Mastiff

Female, 8 mos

East ST Louis, IL

Size

(when grown) Med. 26-60 lbs (12-27 kg)

Details

Story

This pet's adoption fee is sponsored by the Zach Schneider Memorial Fund, created in memory of Zach Schneider, who loved pets and fostered for Gateway Pet Guardians. Meet Hippie! She is new to our rescue and looking for a family to call his own! If you are interested in a meet and greet for adoption for Hippie, please fill out an application on our website at www.gatewaypets.org/adopt. If you are interested in learning more about Hippie or the adoption process at GPG, please email placement@gatewaypets.org All of our dogs and cats will be microchipped, spayed or neutered, and up-to-date on vaccinations at the time of adoption. For more photos of Hippie, follow us on Facebook Gateway Pet Guardians and Instagram @gatewaypets ... #gpgHippie. To view other adoptable pets from our shelter, please visit, www.gatewaypets.org/adopt. Gateway Pet Guardians is proud to offer a variety of mixed breed dogs available for adoption. However, please keep in mind that we rarely know the genetic background of the animals we rescue and, as such, we cannot guarantee the exact breed combinations found within this dog. Therefore, we do not know his/her actual genetic makeup. Just know that this dog is probably a variety of several different breeds that have combined to create one very amazing and unique animal.

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Compton

Mastiff Labrador Retriever

Male, 2 yrs 11 mos

St. Louis, MO

Size

(when grown) -

Details

Good with dogs, Not good with cats, House-trained, Spayed or Neutered,

Story

Compton is a big-hearted, laid-back pup who’s been through a lot and is now searching for the perfect home to call his own. Found abandoned in a park back in January with a collar and lead still attached, it’s clear that he was once someone’s pet—but now he’s looking for a family that truly understands him. Shelter life has been stressful for him, making his search for a loving home even more urgent. While he’s an absolute sweetheart, he thrives best in a calm environment without young kids, as their energy and unpredictability seem to overwhelm him. Otherwise, Compton is truly the bestest boy! This gentle lug is fully crate-trained—though a little hesitant to go in at first, a toy will convince him, and once inside, he settles quietly. He’s also potty trained and will patiently sit by the door to let you know when it’s time to go out. A dream passenger in the car, Compton enjoys gazing out the window or relaxing for the ride. He walks beautifully on a loose leash and has done well with the few dogs he’s met, suggesting he could be a great canine companion with proper introductions. At his core, Compton is just a big teddy bear who deserves all the love in a peaceful, understanding home. If you’re looking for a loyal and affectionate best friend, Compton is ready to be your perfect companion.

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Mr. Bojangles

Mastiff Mixed Breed (Large)

Male, 3 yrs 4 mos

St. Louis, MO

Size

(when grown) -

Details

Spayed or Neutered,

Story

Meet Mr. Bojangles, a distinguished male dog around three years old, who brings both class and a dash of drama to the table! He would like to clarify that the vocalizations you hear from his kennel are not barking, but rather his intensive opera training in progress! Once he's out, this fancy-pants gentleman is incredibly chill and sweet, and he walks like a pro—no pulling, unless nature is making an urgent call. Mr. Bojangles is a certified foodie who appreciates a good gourmet treat but is just as happy with a classic peanut-butter bone. Basically, he’s a loyal companion who is effortlessly refined and ready to serenade his way into your heart!

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Meryl Streep

Mastiff Mixed Breed (Medium)

Female, 1 yr 10 mos

St. Louis, MO

Size

(when grown) Med. 26-60 lbs (12-27 kg)

Details

Good with kids, Good with dogs, Good with cats, House-trained, Spayed or Neutered,

Story

🩷I learned much about adorable Meryl Streep yesterday as we buddied up and attended CARE’S Adoption Event at “Tower Grove Pride” event. This adorable one and a half year-old pup showed her happy self from the moment she jumped in the car and was the perfect backseat rider. 🩷As we walked to CARE’S tent Meryl walked well on the leash. The event was well attended and this sweet pup was friendly and sweet throughout. As participants of all ages came up to say “Hi” and gave her pets she was gentle to everyone. As other dogs passed she was mostly indifferent being content and enjoying the moment. When this precious girl was tired she laid down and fell fast asleep and stayed like that as the action continued all around her. After her short nap we headed back to the car. This precious, perfect girl made the day’s event fun, happy and totally enjoyable for me her sidekick💕 🩷All I could think is this fabulous pup belongs in a loving home and hopefully soon! Meryl Streep, is a treasure and would be a cherished pup for many families. -Her eye condition is called Cherry Eye and is not serious and will be taken care of by CARES clinic when she’s adopted. 🩷She is at CARE STL for you to meet and possibly fall in love just like me🩷🐾XOXO

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Use the search tool below to browse adoptable Mastiff puppies and adults Mastiff in O Fallon, Illinois.

Mastiff puppies and dogs in O Fallon, Illinois

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Mastiff puppies and dogs in O Fallon, Illinois

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Adopt a Mastiff near you in O Fallon, Illinois

We don't see any Mastiffs available for adoption right now, but new adoptable pets are added every day. Try a different search below!

Or, how about these Mastiffs in cities near O Fallon, Illinois

These Mastiffs are available for adoption close to O Fallon, Illinois.

Search for a Mastiff puppy or dog

Mastiff puppies and dogs in nearby cities

Related breeds in O Fallon, Illinois

Mastiff shelters & rescues in O Fallon, Illinois

Looking for a specific shelter or rescue?

Want to learn more about adopting a Mastiff puppy or dog?

Mastiff basics

Mastiff basics