When he was three years old, Emerson's father complained that the child could not read well enough. Then in 1811, when Emerson was eight years old, his father died. He attended Boston Latin School. In October 1817, at the age of 14, Emerson went to Harvard University and was appointed President's Freshman, a position which gave him a room free of charge. He waited at Commons, which reduced the cost of his board to one quarter, and he received a scholarship. He added to his slender means by tutoring and by teaching during the winter vacations at his Uncle Ripley's school in Waltham, Massachusetts.

After Emerson graduated from Harvard in 1821, he assisted his brother in a school for young ladies established in their mother's house; when his brother went to Göttingen to study divinity, Emerson took charge of the school. Over the next several years, Emerson made his living as a schoolmaster, then went to Harvard Divinity School, and emerged as a Unitarian minister in 1829. A dispute with church officials over the administration of the Communion service, and a reticence for public prayer led to his resignation in 1832. A year earlier his young wife and reputed one true love, Miss Ellen Louisa Tucker, died in April 1831.

In 1832–33, Emerson toured Europe, a trip that he would later write about in English Traits (1856). During this trip, he met Wordsworth, Coleridge, John Stuart Mill, and Thomas Carlyle. Emerson maintained a correspondence with Carlyle until Carlyle's death in 1882. He served as Carlyle's agent in the U.S.

In 1835, Emerson bought a house on the Cambridge Turnpike, in Concord, Massachusetts. He quickly became one of the leading citizens in the town. He also married his second wife Lydia Jackson there.

In September 1836, Emerson and other like-minded intellectuals founded the Transcendental Club, which served as a center for the movement, but didn't publish its journal The Dial, until July 1840. Emerson published his first essay, Nature, anonymously in September 1836. While it became the foundation for Transcendentalism, many people at the time assumed it to be a work of Swedenborgianism.

In 1838 he was invited back to Divinity Hall, Harvard Divinity School, for the school's graduation address, which came to be known as his Divinity School Address. His remarks managed to outrage the establishment and shock the whole Protestant community at the time, as he proclaimed Jesus a great man, but not God. For this, he was denounced as an atheist, and a poisoner of young men's minds. Despite the roar of his critics, he made no reply, leaving it to others for his defense. He was not invited back to speak at Harvard for another 40 years, but by the mid 1880s his position had become standard Unitarian doctrine.

Early in 1842, Emerson lost his first son, Waldo, to scarlet fever. Emerson wrote about his grief in two major works: the poem "Threnody", and the essay "Experience". In the same year, William James was born, and Emerson agreed to be his godfather.

Emerson made a living as a popular lecturer in New England and the rest of the country outside of the South. During several scheduled appearances that he was not able to make, Frederick Douglass took his place. Emerson spoke on a wide variety of subjects. Many of his essays grew out of his lectures.

Emerson associated closely with Nathaniel Hawthorne and Henry David Thoreau and often took walks with them in Concord. Emerson encouraged Thoreau's talent and early career. The land on which Thoreau built his cabin on Walden Pond belonged to Emerson. While Thoreau was living at Walden, Emerson provided food and hired Thoreau to perform odd jobs. When Thoreau left Walden after two years' time, it was to live at the Emerson house while Emerson was away on a lecture tour. Their close relationship fractured after Emerson gave Thoreau the poor advice to publish his first book, A Week on the Concord and Merrimack Rivers, without extensive drafts, and directed Thoreau to his own agent who made Thoreau split the price/risk of publishing. The book was a flop, and put Thoreau heavily into debt. Eventually the two would reconcile some of their differences, although Thoreau privately accused Emerson of having drifted from his original philosophy, and Emerson began to view Thoreau as an anti-social misanthrope. Emerson's eulogy of Thoreau is largely credited with the latter's negative reputation during the 19th century.

Emerson was noted as being a very abstract and difficult writer who nevertheless drew large crowds for his speeches. The heart of Emerson's writing was his direct observations in his journals, which he started keeping as a teenager at Harvard. The journals were elaborately indexed by Emerson. Emerson went back to his journals, his bank of experiences and ideas, and took out relevant passages, which were joined together in his dense, concentrated lectures. He later revised and polished his lectures for his essays.

He was considered one of the great orators of the time, a man who could enrapture crowds with his deep voice, his enthusiasm, and his egalitarian respect for his audience. His outspoken, uncompromising support for abolitionism later in life caused protest and jeers from crowds when he spoke on the subject. He continued to speak on abolition without concern for his popularity and with increasing radicalism. He attempted, with difficulty, not to join the public arena as a member of any group or movement, and always retained a stringent independence that reflected his individualism. He always insisted that he wanted no followers, but sought to give man back to himself, as a self-reliant individual. Asked to sum up his work late in life, he said it was his doctrine of "the infinitude of the private man" that remained central.

Like many of his fellow American Transcendentalists of the 19th century, Emerson was strongly influenced by the Vedas, and much of his writing has strong shades of nondualism. One of the clearest examples of this can be found in his essay, "The Over Soul":

"We live in succession, in division, in parts, in particles. Meantime within man is the soul of the whole; the wise silence; the universal beauty, to which every part and particle is equally related, the eternal ONE. And this deep power in which we exist and whose beatitude is all accessible to us, is not only self-sufficing and perfect in every hour, but the act of seeing and the thing seen, the seer and the spectacle, the subject and the object, are one. We see the world piece by piece, as the sun, the moon, the animal, the tree; but the whole, of which these are shining parts, is the soul."

Montaigne strongly influenced Emerson by his early reading of the French essayist. From those compositions he took the conversational, subjective style and the loss of belief in a personal God. He never read Kant's works, but, instead, relied on Coleridge's interpretation of the German Transcendental Idealist. This led to Emerson's non-traditional ideas of soul and God.

Emerson is buried in Sleepy Hollow Cemetery, Concord.