Channing was born in Boston, Massachusetts to a prominent Unitarian family; his uncle William Ellery Channing (the elder) was the pre-eminent Unitarian theologian of the early nineteenth century. William Henry Channing, along with the younger Ellery Channing, was a Transcendentalist. He was a member of the Transcendental Club and corresponded with Ralph Waldo Emerson.

Among his inspirational writings, one piece, his "Symphony", is well-known:

To live content with small means; to seek elegance rather than luxury, and refinement rather than fashion; to be worthy, not respectable, and wealthy, not, rich; to listen to stars and birds, babes and sages, with open heart; to study hard; to think quietly, act frankly, talk gently, await occasions, hurry never; in a word, to let the spiritual, unbidden and unconscious, grow up through the common -- this is my symphony. Channing was, in 1863 and 1864, the Chaplain of the United States House of Representatives.