In addition to ample doses of repetition, anaphora, and allusions to Sherlock Holmes and Napoleon, this comic poem uses the following poetic devices.

Rhyming couplets convey a pleasing, sing-song sense of rhythm that helps structure the poem, such as "paw" and "law" and "despair" and "there." Eliot also uses alliteration to create rhythm. Alliteration puts words beginning with the same consonant in close proximity: an example would be the repeated "f" sounds in "footprints," "found," and "file" in stanza five.

The speaker adopts a hyperbolic voice, which, along with the sing-song rhymes, gives the poem its tone of light-hearted humor. Hyperbole or exaggeration, is critical to humor, and this speaker lays it on thickly, crediting to the ever-missing Macavity increasingly larger and more absurd crimes. Macavity moves from being responsible for missing milk to being accused of stealing important Foreign Office treaties. The absurdity is underscored as the absence of evidence of Macavity's presence at these crime scenes becomes evidence of his crime.

Macavity's name is a pun on a cavity (a hole) and being missing. It reflects the cat's mysterious absences.

Eliot also uses imagery, which is description employing any of the five senses of sight, sound, touch, taste, or smell in the poem. For instance, we are offered a visual description of Macavity:

a ginger cat, he’s very tall and thin;
You would know him if you saw him, for his eyes are sunken in.

This description morphs into personification, for Macavity comes to look more like a human being than a cat:

His brow is deeply lined with thought, his head is highly domed

Eliot's poetic devices successfully entertain us in this comic romp.

T. S. Eliot uses poetic devices like repetition, anaphora, and allusion to illustrate the treacherousness and ingenuity of his subject. The repetition within the poem comes in the form of Macavity's name, which is repeated almost like a chant at times ("Macavity, Macavity, there's no one like Macavity"). The famous line "Macavity's not there!" is repeated several times throughout the poem as well, emphasizing Macavity's skill in evading any authority that would thwart his schemes. The repetition also gives Macavity the aura of a legendary figure, someone larger than life and beyond comprehension.

As a rhetorical device, anaphora is closely related to repetition. It too is when a phrase or word is repeated throughout a poem or speech for emphasis, only this repetition is located at the beginning of a clause (ex. "It was the best of times, it was the worst of times."). In "Macavity," Eliot uses anaphora throughout the poem, mainly in using "and" and "or" when cataloging Macavity's various criminal ventures:

And his footprints are not found in any file of Scotland Yard’s.
And when the larder’s looted, or the jewel-case is rifled,
Or when the milk is missing, or another Peke’s been stifled,
Or the greenhouse glass is broken, and the trellis past repair—

These series of conjunctions serve to make Macavity seem all the more accomplished and omnipresent, adding to the mysterious aura about his character. It also makes him seem like an overwhelming opponent, someone no detective or police officer could ever hope to handle.

Lastly, Eliot uses allusion to further sharpen the reader's mental portrait of Macavity. An allusion is a reference to another work, and in "Macavity," allusions to the Sherlock Holmes stories are prominent. From his name to his criminal nature, Macavity is clearly modeled on Holmes's nemesis, Professor Moriarty. Both Moriarty and Macavity are called "the Napoleon of Crime." Macavity is given other such names as well, like "the Hidden Paw," which gives him a sense of notoriety within his own world not unlike his Holmesian counterpart.

The principal poetic devices in "Macavity: The Mystery Cat" are various types of repetition, including anaphora and epistrophe. Above all, Macavity's name is repeated many times, particularly in the recurring line:

Macavity, Macavity, there's no one like Macavity

This allows various intricate feminine rhymes, such as "gravity" and "depravity." The rhymes in the poem are generally very ingenious, reflecting the ingenuity of the subject.

Apart from Macavity's name, various phrases are repeated to rhetorical effect, often in grammatical parallels. The hopelessness of trying to catch Macavity, for instance, is emphasized by the repetition of "you may" followed by the different places in which you might seek the master criminal, all to no avail, since, in another repeated phrase, it invariably turns out that "Macavity's not there."

A less obvious device, but one which will be apparent to aficionados of the Sherlock Holmes stories, is the frequent use of allusion throughout the poem. Macavity is based closely on Conan Doyle's description of Professor James Moriarty. The parallel is drawn in the third stanza, where the physical description of Macavity is closely based on Moriarty, even down to his tendency to sway his head from side to side like a snake. The names of the two criminals are similar, and the comparison is made very clear at the end of the poem, when Eliot applies to Macavity exactly the same description that Holmes uses for his nemesis: "the Napoleon of Crime."