The celebrity homemaker said on her Web site that she was looking forward to returning to work in March and enjoying "many brighter days ahead."
Stewart, 63, was convicted last March of lying to investigators about why she sold stock in a biotech drug maker in December 2001, just before its price plunged. She was allowed to remain free pending appeal but asked to begin serving her time anyway, saying she wanted to reclaim her life.
"While I am away, my updates here will be less frequent, if not altogether impossible," Stewart said in a letter posted on her Web site. "But please know this change is only an unfortunate reflection of my current circumstances, and in no way diminishes my commitment to my life's work or to the friends, colleagues, customers and supporters who make it possible.
"With your good wishes in my heart, I am looking forward to being back at work in March, and to many brighter days ahead."
Stewart, who built a business empire dedicated to stylish living that includes magazines, television shows and a line of home fashions, has said she will miss her pets during her stay in prison, but hoped to be free in time for spring gardening.
Inmates who are sentenced to a year or less are not eligible for early release because of good behavior. Following her prison term, Stewart must serve five months of home confinement.
Like all new inmates, Stewart was photographed, fingerprinted and strip searched. Her personal items were inventoried, said Traci Billingsley, a spokeswoman for the U.S. Bureau of Prisons in Washington.
She was issued clothing that includes khaki-colored trousers, a button-down shirt and black steel-toed boots, as well as a change of bedding and set of towels.
Prisoners are allowed a plain wedding band and a religious medallion, both of which must be worth less that $100, a pair of prescription eye glasses and legal papers.
After being interviewed by prison staff and briefed on the institution's rules, new inmates undergo a two-week orientation, during which work assignments are made.
Famous inmates are nothing new to the town of Alderson, about 270 miles southwest of Washington, D.C. The prison, which opened in 1927, has hosted Billie Holiday, Tokyo Rose, Axis Sally and would-be presidential assassins Squeaky Fromme and Sara Jane Moore.
Yet none has attracted as much attention as Stewart.
As soon as Betty Alderson heard Stewart was coming to town, she got the ball rolling on a money-making deal.
Alderson, who runs a clothing store and gift shop, ordered dozens of shirts with the slogan, "West Virginia Living, it's a good thing," a reference to Stewart's catch phrase. Another style says, "Alderson, West Virginia. A great place to visit."
"It's bringing light to our town and people are coming in to see it and see West Virginia," Alderson, whose great-great-great-great grandfather-in-law founded the town in 1777, said on CBS News' The Early Show.
At the nearest Kmart, two young women weren't happy about all the fuss.
"It's going to be a big ordeal," said one.
"It's drawing people who would never come to Alderson, as well as every other town in the area," said the other.
While in prison, Stewart will forgo five months of her $900,000 yearly base pay from her company, Martha Stewart Living Omnimedia Inc. An employment contract approved Sept. 17 says the company will resume paying her when she leaves prison and is on home confinement.
Behind bars, Stewart will be eligible for jobs that pay 12 cents to 40 cents an hour.
Stewart and her former stockbroker Peter Bacanovic were convicted in March of lying to federal investigators about why Stewart sold 3,928 shares of ImClone Systems Inc. stock on Dec. 27, 2001, the day before a negative announcement about the company that sent the price plunging.
She was sentenced in July to five months in prison and five months of house arrest for obstruction of justice, false statements and for the conspiracy to obstruct justice, make false statements, and commit perjury.
She was allowed to stay free pending appeal but decided to begin serving her time before the appeal was resolved.
"As I announced in September, although my lawyers remain very confident in the strength of my appeal and will continue to pursue it on my behalf, I have decided to serve my sentence now because I want to put this nightmare behind me as quickly as possible for the good of my family and my company," the statement on Stewart's Web site said.
Bacanovic received the same sentence. He remains free during his appeal and has announced no plans to enter prison.