In Down and Out in Paris and London, Orwell follows a penniless British writer through two great European cities as he works seventeen-hour workdays in the squalid kitchens of trendy Parisian restaurants. After working himself ragged and never getting ahead, he tries his luck in London where he lives the life of a vagrant, sleeping in lodging houses and taking charity tea at the Salvation Army. Through these scenes, Orwell explores one of the classic themes in most of his writing, that of man vs. society.

At the beginning of the novel, the narrator is living in Paris, teaching English to pay his bills, but he slowly loses his students and then gets robbed, leaving him enough money to survive for only a week or two. He makes drastic changes in his budget and finds that living in poverty is a complicated ordeal.

The narrator's Russian friend, Boris, is in a similar situation, having injured himself and lost his job. The two friends help each other out, pawning their remaining clothing together and sharing meager meals at one another's apartments. Eventually, the friends find a job at the Hotel X, working as plongeurs in the cellar kitchen.

Working in the hotel opens the narrator's eyes to the squalid conditions behind the scenes at upscale Parisian establishments. The kitchens are full of filth, mediocre ingredients, and poor working conditions, but just on the other side of the wall, the dining rooms are lush, clean, and luxurious.

Boris knows a Russian friend who is opening up a small restaurant called the Auberge de Jehan Cottard and has promised Boris and the narrator jobs. The restaurant is slow to open because the patron has difficulty scraping up enough money for up-front costs, but eventually it opens, and Boris and the narrator begin working there. Working conditions at the Hotel X were wonderful compared with those at the Auberge. Although the pay is the same, working hours are much longer, usually about seventeen hours a day, seven days a week. There is no hot water in the kitchen and nowhere but the floor on which to place the food. After several weeks of this misery, the narrator writes a friend in his native London, asking for help in finding a job there, and the friend replies almost immediately with a prospective job.

The narrator travels to London, but when he arrives he finds that his new employer is out of the country and will not return for at least a month. He doesn't have much money saved from his job at the Auberge de Jehan Cottard, so he immediately pawns some clothes and takes up a life as a vagrant, or tramp, as they're called in the novel.

The narrator learns all about the life of a British tramp. He lives in spikes, lodging houses, even under a bridge when it's necessary. He meets an Irishman named Paddy, and the two become friends, traveling together from spike to spike. The narrator spends some nights at the Salvation Army shelters, which he despises, and he thinks of ways that the legal system in England could change in order to help tramps to lead more productive and satisfactory lives.

In the end, the narrator does get a job when the employer returns to England, but he has changed his perspective about many things. He no longer judges vagrants or thinks that they're not "working" when he sees them standing around waiting for the shelters to open. He gains a great respect for people who can see through their trials and be happy anyway. And he doesn't expect beggars to be grateful when he gives them a penny.