"The Highwayman" is a ballad written in three parts. The first part consists of six sestets (six-line) stanzas, the second part of nine sestets, and the third of two.
The poet develops a comforting sense of rhythm through using a regular rhyme scheme: AABCCB. What makes the scheme slightly unusual is that the "C" rhymes are always the same word. In stanza two, for example, the "A" rhymes are at the end of the first two lines ("chin" and "skin"), the "B" rhymes at the end of the third and sixth line ("thigh" and "sigh"), while the "C" rhyme in lines four and five is the same word ("twinkle"). This pattern repeats throughout the poem. As the poem does not have the regular two-line refrain we often associate with a ballad, these repeated words create a sense of refrain. Two lines repeat as well, also creating a refrain: "Plaiting a dark red love-knot into her long black hair" appears in stanzas three and eleven, and "came riding" appears twice in stanza one and once in stanza six.
The poem's lines are also regular, each with six beats. The beats are either two syllables, called iambs, or three syllables, known as an anapests. We can see this play out in the first line:
The wind was a torrent of darkness among the gusty trees
"The wind" is an iamb, with the emphasis falling on wind, as in "the WIND," while the second and third units are anapests: "was a TOR/rent of DARK." This pattern is a little unusual, but overall the formal structure of the poem is very traditional.