Series beginning with M
- Mabel Jones
- Mac B. Kid Spy
- Macdonald Hall
- Madame Pamplemousse
- Maddy Yip
- Maggie Blue
- Maggie McKinley
- Maggie Sparks
- Magic Animal Friends
- Magic Ballerina
- Magic Hour
- Magic Keepers
- Magic Kitten
- Magic Mirror
- Magic Misfits
- Magic Molly
- Magic on the Map
- Magic Ponies
- Magic Pony
- Magic Pony Carousel
- Magic Potions Shop
- Magic Puppy
- Magic Thief
- Magic Tree House - Merlin Missions
- Magic Tree House - UK series
- Magic Tree House - USA Series
- Magic Trix
- Magical Kingdom of Birds
- Magical Mix-ups
- Magical Rescue Vets
- Magical Venice
- Magicalia
- Magicborn
- Magician's House
- Magisterium
- Magnificent 12
- Magnificent Mabel
- Magnificent Moon Hare
- Magnificent Mya Tibbs
- Magnus Chase and the Gods of Asgard
- Magpie Society
- Maisie
- Maisie Hitchins
- Maisie Morris
- Major and Mynah
- Make Friends, Break Friends
- Malediction Trilogy
- Malichea Quest
- Mallory Vayle
- Malory Towers
- Malory Towers Continuation Series
- Mango and Bambang
- Mapmakers
- Marge in Charge
- Mariah Mundi
- Marie Curious, Girl Genius
- Mariella Mysteries
- Marietta's Magic Dress Shop
- Marius Grey
- Mark Anchovy: Pizza Detective
- Mark of the Thief
- Marlow Family
- Marnie Midnight
- Mars Trilogy
- Marsh Road Mysteries
- Marshmallow Pie
- Marty Frye, Private Eye
- Marty McGuire
- Marty Pants
- Marv
- Marvellerverse
- Marvellous Granny Jinks and Me
- Marvin Redpost
- Mary Poppins
- Mason Mooney
- Master Crook's Crime Academy
- Matched
- Mates, Dates
- Matt Millz
- Matthew Martin
- Maudlin Towers
- Max and Chaffy
- Max and Molly's Guide to Trouble
- Max and the Midknights
- Max Cassidy Adventures
- Max Einstein
- Max Flash
- Max Magic
- Max Remy Spy Force
- Max the Detective Cat
- Max Tilt
- Maximum Ride
- Maximum Ride - Hawk
- Maya
- Maya Brown Missions
- Mayfair Mysteries
- Mayfly
- Mayowa
- Maze Runner
- Meadow Vale Ponies
- Measle Stubbs
- Mediator Series
- Medusa Project
- Meesh the Bad Demon
- Meet the Kreeps
- Meet the Maliks – Twin Detectives
- Meg and Merlin
- Mega Robo Bros
- Mel Beeby, Agent Angel
- Mel Foster
- Memoirs of a Neurotic Zombie
- Mennyms
- Mercy Watson
- Merlin
- Mermaid Academy
- Mermaid Curse
- Mermaid Rock
- Mermaid School
- Mermaid SOS
- Mermaids Rock
- MerTales
- Messenger of Fear
- Metawars
- Mia - Umbra Tales
- Michael
- Mickey
- Mickey Bolitar
- Mickey Sharp
- Middle School
- Middle School Bites
- Midnight Hour
- Midnight Library
- Midnight Magic
- Midvale Academy
- Millennium's Rule
- Million Dollar Mates
- Milly Molly Mandy
- Milton
- Mina Mistry Investigates
- Mind & Me
- Mindy Kim
- Ministry of Unladylike Activity
- Minivers
- MiNRS
- Mirabelle
- Miraculous Sweetmakers
- Mirror Chronicles
- Mirror Mirror
- Mirrorscape
- Misadventures of Max Crumbly
- Misadventures of Merdyn the Wild
- Misadventures of Tallulah Casey
- Misewa Saga
- Misfitz Mysteries
- Miss Cat
- Miss Mary-Kate Martin's Guide to Monsters
- Miss Peregrine's Peculiar Children
- Missing
- The Missing
- Missing Link Trilogy
- Missing Persons Mysteries
- Mission Fox - e-book only series
- Mission Survival
- Mission: Microraptor
- Mister Max
- Mistress of the Storm
- Model Under Cover
- Modern Faerie Tales
- Molly Malone & Bram Stoker
- Molly Moon
- Momo Arashima
- Monday Night Football Club
- Monkeys
- Monster
- Monster Blood Tattoo
- Monster Bogey
- Monster Doctor
- Monster Doughnuts
- Monster High
- Monster High: Ghoulfriends Forever
- Monster Hunting For Beginners
- Monster Makers
- Monster Max
- Monster Republic
- Monster Support Group
- Monster Who Wasn't
- Monsters of Verity
- Monstertown Mystery
- Monstrous Devices
- Monstrous Maud
- Montgomery Bonbon
- Month of Magic
- Montmorency
- Monty's Island
- Moojag
- Moomin Series
- Moon Base Alpha
- Moon Girl
- Moon Riders
- Moonchild
- Moone Boy
- Moonlight Magic Club
- Moonlight Riders
- Morgana Mage
- Morganville Vampires
- Mort the Meek
- Mortal Chaos
- Mortal Engines
- Mortal Gods
- Mortal Instruments
- Mortality Doctrine Series
- Mortimer Keene
- Mouse Heart
- Mouse Watch
- Mouseheart
- Mouselets of Deptford
- Movie Maniacs
- Moving Times
- Mr Bambuckle's Remarkables
- Mr Dog
- Mr Galliano's Circus
- Mr Gum
- Mr Lemoncello
- Mr Majeika
- Mr Penguin
- Mrs. Smith's Spy School for Girls
- Ms Wiz
- Ms. Frogbottom's Field Trips
- Muddle Earth
- Muddlemoor Mysteries
- Muddy Paws
- Mum Hunt
- Mummy Fairy and Me
- Muncle Trogg
- Murder at Snowfall
- Murder Most Unladylike Mini Mysteries
- Murder Most Unladylike Mystery
- Murder Notebooks
- Murder Puzzle Mysteries
- Murray and Bun
- Museum Kittens
- Museum Mystery Squad
- Mustang Mountain
- My Babysitter Is a Robot
- My Big Fat Smelly Poo Diary
- My Big Fat Zombie Goldfish
- My Brother Is a Superhero
- My Brother's Famous Bottom
- My Desperate Love Diary
- My Funny Family
- My Furry Foster Family
- My Laugh-Out-Loud Life
- My Magical Pony
- My Mum Is A Spy
- My Naughty Little Puppy
- My Naughty Little Sister
- My Secret Unicorn
- My Sister the Vampire
- My Super Sister
- My Swordhand is Swinging
- My Weird School
- My Weird School Daze
- My Weird School Specials
- My Weirder School
- My Weirder-est School
- Myrtle Hardcastle Mystery
- Mysteries at Sea
- Mysteries of the Septagram
- Mysterious Benedict Society
- Mysterium
- Mystery Series - The Five Find-Outers
- Mystery Series by Paul Moxham
- Mystic City
- Mystwick School
- Mythics
- Mythos Academy