In the books

 Harry Potter and the Philosopher's Stone

Eleven-year-old Malfoy makes his first appearance in Diagon Alley at Madam Malkin's robe shop, in contrast to the film where Harry first meets him when arriving at school. Malfoy, remarkably, is the only magical person to attempt to befriend Harry without knowing who he is, although he immediately alienates Harry with his arrogant conversation. When he says he is planning to persuade his father to buy him a new racing broom, it strongly reminds Harry of his spoiled cousin Dudley Dursley. Draco also disparages Hagrid, whom Harry has already befriended. Finally, Malfoy asks if Harry's parents are "our kind" (wizards), then tells him that he thinks "the other sort" (Muggleborns) shouldn't be allowed at Hogwarts because "they've never been brought up to know our ways." Unknown to Malfoy, Harry, although the son of two magical parents, is such a person. It is at this time that Malfoy receives his wand, which is, according to Ollivander, made of "hawthorn and unicorn hair. Ten inches precisely. Reasonably springy." The boys part without introductions, but meet again on the Hogwarts Express. After Malfoy ridicules Ron Weasley's family, Harry rejects his offer of friendship, and their mutual dislike is born.

Draco is portrayed as a rather cowardly bully who uses psychological manipulation and verbal taunts to denigrate his victims. Despite his cockiness, Malfoy is physically nonviolent, and his sharp tongue often gets him into trouble when Crabbe and Goyle are not around to protect him.

Malfoy is the favorite of Severus Snape, the Potions Master and Head of Slytherin House. As such, Draco often gets away with behavior in Potions class that would land Harry or another Gryffindor in detention.

 Harry Potter and the Chamber of Secrets

Draco is now 12 years old and is the new Seeker for the Slytherin Quidditch team. Hermione Granger speculates that his father bought his way in by donating high-quality Nimbus 2001 brooms to the Slytherin team. Malfoy retorts by calling her a Mudblood, which provokes an immediate, violent response from all the Gryffindors present except Harry and Hermione herself, who, being both raised by Muggles, do not know what the term means. The new brooms allow the Slytherin team to outscore the Gryffindor chasers in the year's first match, but ultimately, Harry catches the Snitch, winning the match for Gryffindor.

Malfoy introduces open prejudice against Muggle-born wizards by calling Hermione a Mudblood, which is the word's first appearance in the series. Because of his expressed contempt for Muggle-borns, Harry and his friends suspect Malfoy is the Heir of Slytherin who opened the Chamber of Secrets. Harry and Ron, using Polyjuice Potion to assume the forms of Crabbe and Goyle, discern that Malfoy is not the Heir, though he does admit that he would like to know who the Heir was so that he could help him.

Harry Potter and the Prisoner of Azkaban

At the start of Book 3, Malfoy has turned 13 years old. During new instructor Hagrid's first Care of Magical Creatures class, the hippogriff Buckbeak attacks Malfoy after he insults it in an attempt to once again undermine Harry. Malfoy milks the "injury," giving Slytherin a chance to postpone their match against Gryffindor until later in the year. He and his father also use the incident in an attempt to get Hagrid fired. Although Hagrid is cleared, Buckbeak is sentenced to death (but is later rescued by Hermione and Harry). Hermione slaps Malfoy when he mocks Hagrid for crying over Buckbeak's sentence (but in the movie version of this scene Hermione punches Malfoy in the nose).

Malfoy lets on that he knows more about Sirius Black than Harry does, taunting Harry by saying vague things about what he would have done to get revenge on Sirius Black. Harry, as yet unaware of the past Draco alludes to, ignores him.

 Harry Potter and the Goblet of Fire

Fourteen-year-old Draco Malfoy meets Harry Potter on the train to Hogwarts School of Witchcraft and Wizardry and asks if Harry is going to take advantage of this latest opportunity to show off. Realizing that Harry and his friends are unaware of the impending Triwizard Tournament, Draco then makes disparaging remarks regarding Ron's father, suggesting that the Ministry does not discuss important affairs in the presence of their minor staff members.

When Harry is chosen as one of the Triwizard Tournament Champions, Draco creates the "Support Cedric Diggory" badges for the Triwizard Tournament and shows them to Harry. When the badges are touched, the phrase is replaced with a second phrase, "Potter Stinks." He also gives malicious and often false information about Harry Potter and Hagrid to Rita Skeeter, a journalist and illegal Animagus who uses unethical methods to gain information for her stories, often eavesdropping while in her animagus form, a beetle.

Barty Crouch Junior (disguised as Alastor Moody), who hates all Death Eaters who- like Lucius Malfoy- escaped punishment for their crimes, singles Draco by transforming him into a ferret and slamming him against the floor.

At the Yule Ball, Malfoy is accompanied by Pansy and wears black velvet robes with a high collar, which, in Harry's opinion, makes him look like a vicar.

 Harry Potter and the Order of the Phoenix

Draco Malfoy is now 15 years old. He has been selected as a Prefect along with Pansy, and joined Headmistress Umbridge's Inquisitorial Squad, which plays an important part in the exposure of Dumbledore's Army, a Defence Against the Dark Arts group led by Harry. Malfoy personally caught Harry, hitting him with a trip jinx and alerting Umbridge, which earned Slytherin fifty house points. He also caught Harry trying to break into Umbridge's office and looks eager to see Harry punished, although he has no way of knowing that Umbridge plans to subject Harry to the Cruciatus Curse. After the events at the Department of Mysteries, during which Malfoy's father and several others are captured and sentenced to Azkaban prison, Malfoy twice attempts to corner Harry to get revenge. In the first instance, he is interrupted by the arrival of Professors Snape and McGonagall; in the second attempt on the Hogwarts Express, he is jinxed by several members of Dumbledore's Army. It is also revealed, through a lesson involving thestrals, that Draco has never "seen death."

Draco causes Harry, Fred and George Weasley to be banned from the Gryffindor Quidditch team after taunting the two about their mothers after losing the game, prompting them to physically attack him.

 Harry Potter and the Half-Blood Prince

Malfoy is 16 years old during his sixth year at Hogwarts. Before school starts, Harry encounters Malfoy in Diagon Alley at Madame Malkin's Robes shop, after which Malfoy and his mother, Narcissa Malfoy, leave, refusing to buy from an establishment serving Muggle-borns and their sympathisers. Harry and his friends, hidden by Harry's Invisibility Cloak, later see Malfoy at Borgin & Burkes, a shop featuring dark artifacts. His activity there leads Harry to suspect Draco has been branded with the "Dark Mark," the Death Eaters' sign. On the Hogwarts Express, Harry uses his Invisibility Cloak to spy on Malfoy and four other Slytherins—Pansy, Crabbe, Goyle, and Blaise Zabini—and overhears Malfoy discussing a task given to him by Lord Voldemort. Malfoy realizes that Harry is listening, and after everyone else in the compartment leaves, immobilizes him and breaks his nose, leaving Harry stranded on the train to later be saved by Nymphadora Tonks (who is, incidentally, Draco's cousin).

Harry spends much of the school year spying on Malfoy, using the Invisibility Cloak, the Marauder's map and the house-elves Kreacher and Dobby, but finds he is unable to track his movements once Malfoy enters the Room of Requirement. When Katie Bell is nearly killed by a cursed necklace bought from Borgin & Burkes, and Ron is poisoned by mead intended for Dumbledore, Harry suspects Draco is behind both attacks. Harry later finds Malfoy crying to Moaning Myrtle in her bathroom. When Malfoy sees Harry, the two attempt to jinx each other. As Malfoy attempts to cast the Cruciatus Curse, the quicker Harry uses the obscure Sectumsempra spell on Malfoy, slashing his face and chest and causing him to bleed heavily. Snape arrives almost immediately thereafter and takes Malfoy to the infirmary.

When Harry and Dumbledore return to Hogwarts after a journey to find a Horcrux - during which Dumbledore was weakened by the effects of an unnamed potion found at the site of the Horcrux - they find the Dark Mark hovering over the Astronomy Tower. After landing on the tower, Malfoy ambushes and disarms Dumbledore, although Dumbledore had a crucial second to first immobilize Harry under his Invisibility Cloak to keep him safe. Dumbledore calmly converses with Malfoy and gets him to reveal the ways he attempted to murder him during the year. Malfoy explains that Lord Voldemort ordered him to murder Albus Dumbledore, and that he had been mending the broken Vanishing Cabinet in the Room of Requirement to allow Voldemort's Death Eaters to enter through it and invade Hogwarts. Dumbledore correctly surmises that as the school year progressed, Draco believed he would be unable to fix the cabinet. In desperation, he unsuccessfully attempted to curse and then poison the headmaster, nearly killing Katie Bell and Ron Weasley in the process. Finally successful, he tells Dumbledore that several Death Eaters have entered the school and set off the Dark Mark to lure Dumbledore to the tower. Dumbledore tells Draco that he knows that he is unwilling to kill the Headmaster, despite having him cornered and defenseless. Even after he is joined by several older Death Eaters, Malfoy makes no move to kill Dumbledore and lowers his wand. Instead, Snape arrives on the scene and he shoves Malfoy out of the way and kills Dumbledore himself. He and Draco, initially pursued by Harry Potter, escape the school. Harry believes Draco would have spared Dumbledore, and even though he still dislikes his rival, Harry feels sympathetic towards Draco and realizes he was forced to do Voldemort's bidding or face the potential murder of himself and his family.

For the first time in the series, Draco is portrayed in something of a sympathetic light. In Draco's conversation with Dumbledore we do not see a bully or sadist - rather, we note him as a terrified boy, who has no appetite for true evil but has been forced into it through threats and coercion. His intense protectiveness of his family, a trait found in all of the Malfoys but particularly Narcissa, is also evident.