He graduated from Harvard College in 1800, and for the next three years went to London to study art in the Royal Academy, of which Benjamin West was then the president.

Samuel F. B. Morse was one of Allston's art pupils. Morse even accompanied Allston to Europe in 1811.

He then studied in Rome, and finally settled in London, where he won fame and prizes for his pictures.

In 1818 he returned to the United States and lived in Cambridge, Massachusetts where he died at age 64.

One of Allston's most popular works was a painting called Moonlit Landscape. Other on of his works was Belshazzar's Feast. It currently hangs in the Boston Athenaeum. Allston hoped that Belshazzar's Feast would be his greatest work he would create. During the time he worked on Belshazzar's Feast Allston made many paintings just to get by. One of those paintings was Moonlit Landscape. After the failure of Belshazzar’s Feast, Allston was crushed. What would add an extra sting to his wound was the fact that Moonlit Landscape was so popular. He still held up his opinion until his death that Belshazzar’s Feast was his best painting despite what anyone else thought.

Moonlit Landscape was painted in Boston in 1819. This painting was typical of Allston, landscapes were a common theme of this Romantic painter. The lines were made with delicate strokes. The direction of the lines are predominately horizontal, but the clouds, river and bank also incorporate the use of many curvy lines.

When you first see the picture, your eyes are instantly drawn to the circular swirling clouds that frame the moon. The moon is located at the center of the painting. Almost being too bright, the moon is illuminated by a bright ghostly glow around it. One reason the moon could have been so bright was in order to let the viewer see the scene under the night’s sky. Otherwise if the moon was a realistic glow, you wouldn’t be able to see anything you can see in the painting.

In the painting, there is a grassy valley with a river running straight through the middle of it. Located on the right of the river is a wood. To the left of the river there is a bank with two boats on it. One boat is a small row boat behind the bigger boat. The other boat is a sail boat with its mast pointed upward. A man can be seen running away from the boats on a pathway away from the viewer’s eye. It is unclear why he is running but it looks as though it’s important that he leave the bank immediately. Beyond the boats and the running man, a town can faintly be seen in the background. The viewer can see a mountain range way off in the distance.

Allston clearly used atmospheric perspective in his piece with the mountains. You can see the mountains off in the distance, and the man running in the background is another use of this technique. He isn’t as large as other people that are in the painting. The painting can be described as deep, you can see for miles and miles. It is a fairly crowded piece and there are many subjects in it. It is a naturalistic painting. There is also shading and shadowing throughout the entire painting. The shadowing was evident in the fog put throughout the painting.

There seems to be fog or night mist throughout the painting that makes it hard to see the village. This adds part of the mystery and dream-like state to the painting. The town doesn’t look like a huge city with tall buildings, but a quaint town located in some village. Right beside the village, there is a bridge that leads from the pathway the man is running on, to on the other side of the river and into the woods. The bridge does not look modern in any way but was made in a simple fashion. There are three arched post that go into the river’s water to hold up the bridge. There’s no railing or anything above the bridge’s road, just a simple way to get over the river. There are other people in the painting besides the man running.

Closer to the viewer’s eye, on the left side of the bank, is a man wearing a hat. He is on a horse and appears to be conversing with a family of three. There is a woman closest to the man on the horse with her hand held up in pointing farther down the bank towards the vicinity of the man running. She looks to another man, located on her left, and motions this gesture towards the running man. To her left the man is looking in the direction of where her hand is pointing. This gesture the woman gives with her hand pulls the viewer’s eye towards the man, giving him more attention. The man beside her is also holding onto a small child’s hand. The child is following after the man and woman, trying to keep up. Moonlit Landscape is a stunning piece and quite lovely.

He was the uncle of the artists George Whiting Flagg and Jared Bradley Flagg, both of whom studied painting under him.

He also wrote a good deal of verse including The Sylphs of the Seasons, etc. (1813), and The Two Painters, a satire. He also produced a novel, Monaldi.

The west Boston neighborhood of Allston is named for him.