William and Kate, she in a blue shift dress and he in a blue suit and red tie, were pictured on the runway boarding the Royal Canadian Air Force aircraft at London's Heathrow Airport.
The Duke and Duchess of Cambridge, as they are formally known, are expected to land at 2:00 p.m. local time in Ottawa, the first stop in their whirlwind visit to seven Canadian cities before they head to the U.S.
Upon their arrival, the royal newlyweds will participate in a brief ceremony featuring a piece of music created just for them by the Pipe Major, or director of bagpipe music. The piece is called "St. Andrews Courtship," a nod to the university in Scotland where the couple met and fell in love.
Also designed especially for the royal couple in honor of their first trip to North America together is a personal flag for Prince William.
The flag, unveiled by Canada's prime minister and approved by both the Queen and William, is the first to be created by Canada for a member of the royal family since 1962, when the queen adopted a personal flag for her own use in Canada.
William's flag features three maple leaves, from Canada's national tree. It will adorn the cockpit of the jet carrying the royal couple when they touch down on Thursday afternoon, and will fly from their cars and all buildings they visit or stay in during their trip.
The Royal Itinerary
The North American agenda for the newlyweds, married just this April in a lavish royal wedding, shows the young couple has already mastered one ingredient to a long, happy marriage: compromise.
In Canada, for example, William and Kate, both 29, will visit Prince Edward Island, the location featured in Middleton's favorite childhood book, "Anne of Green Gables." William will have a chance to show his skills as a helicopter rescue pilot by taking part in a water landing demonstration.
And while in Los Angeles, the couple made sure to include a charity polo match, for him, and a tour of an inner-city arts program, for her.
Upon arrival today in Ottawa, the couple will head directly to Canada's National War Memorial for a wreath-laying ceremony.
Then they will travel to Rideau Hall, the official residence of Canada's governor general, David Johnston, where they will be welcomed by Prime Minister Stephen Harper with full military honors, including a 21-gun salute.
Prince William will speak at the official welcome ceremony at Rideau Hall, where crowds are already said to be gathering, before departing for a barbecue to mark the achievements of young Canadians.
Crowds on the Ottawa leg of the couple's tour alone are expected to exceed half a million, a sign of the country's excitement over the duke and duchess' arrival.
It's Middleton's first visit to Canada; William has traveled there before. The trip will be closely followed by the media, with nearly 1,400 journalists accredited to cover the visit.
Canada is a member of the Commonwealth and Queen Elizabeth II, William's grandmother, is its head of state.
"Canada is very much part of her family's story," a royal source told People magazine.
On Friday, Kate and William will be celebrating Canada's birthday, the same day William's mother, the late Princess Diana, would have turned 50.
The duke and duchess's plans for Canada Day, the official holiday marking the formation of Canada into a single country, includes attending a citizenship ceremony and a parade on Parliament Hill, the public grounds of Canada's parliament buildings.
The prince is scheduled to speak at a number of their Canada Day stops, while Kate is not.
The royals are scheduled to arrive in the French-speaking province of Canada on Saturday, July 2, flying into Montreal and traveling to Quebec City on an overnight cruise ship.
In Montreal, they are to attend a tree-planting ceremony, meet with veterans and their families, visit the largest maternity center in Canada and attend a cooking workshop at a tourism and hotel institute.
They will arrive in Quebec City the next morning, joining the crew of the HMCS Montreal in Sunday worship. Afterward, they are scheduled to visit an organization that caters to street youths, attend a military ceremony and join in the 375th-year celebration of the city of Levis.
Prince Edward Island
On July 4, the royal couple is scheduled to arrive on Prince Edward Island.
It is also here where William, a member of the Royal Air Force's search and rescue force, is to participate in a training session for an emergency sea landing by the same Sea King helicopter he flies back home in Britain.
The royal highnesses will also learn about the island's aboriginal, Acadian and Celtic ancestry, as well as its culinary traditions by putting on aprons for a cooking demonstration.
The next stop on the duke and duchess's itinerary will be the uppermost reaches of Canada, the rugged Northwest Territories.
Arriving July 5, they are to meet with the region's aboriginal youth and leaders and take part in activities such as traditional drumming, dancing and canoeing.
The final stop in William and Kate's Canada tour, Calgary, will be their most down-home.
On July 7, the couple are to be greeted at the airport with white cowboy hats, a nod to the city's western hospitality. They will then head to the University of Calgary to learn about Canada's cutting-edge health research.
But the real fun takes place that evening, when the duke and duchess are scheduled to attend the Calgary Stampede, the world's largest rodeo and self-proclaimed "Greatest Outdoor Show on Earth"-- including a bull-riding demonstration and a chuckwagon race.
The next morning, they are to kick off the Calgary Stampede Parade, the second largest parade in the world, and travel in the motorcade.
That afternoon, the royals are scheduled to say farewell to Canada and hello to America.
Next Stop: Hollywood
The duke and duchess' visit to America will take them to only one state, California, and their short weekend stay in the Los Angeles area is being highlighted by their handlers as a working visit, not a time to mix with celebrities.
"The palace is really playing down any big introductions to A-list stars," ABC News royal correspondent Katie Nicholl said on "Good Morning America." "These tours are fun but hard work. It's really about forging ties between America and Great Britain."
The royal couple's itinerary calls for them to hit the ground running as soon as they arrive at the Los Angeles airport July 8. First on their agenda is an evening business event at the Beverly Hilton Hotel, where they will shake hands with California politicians and high-profile businessmen and women to promote U.K. trade and investment.
The business affair will be followed by a reception at the British Consular-General residence in Hancock Park.
On July 9, the duke will play in a charity polo match at the Santa Barbara Polo Club to benefit the American Friends of the Foundation of Prince William and Prince Harry, while his bride will hand out the winning trophy.
So far, reports the UK's Daily Mail, about 1,000 VIP tickets have been sold to the polo match along with about 400 general admission passes, raising nearly $4.4 million for the Foundation.
That evening, their trip will take a more red carpet turn when the royals rub shoulders with stars from British television, film and theater at a black-tie British Academy of Film and Television Arts dinner at L.A.'s Belasco Theatre.
Prince William (who's also the president of BAFTA) will give a speech at the gala, which is focused on spotlighting emerging British talent and building partnerships between Hollywood and up-and-coming British actors.
Day three begins with more philanthropic work, starting with an event to support Tusk USA, an organization that raises funds for African wildlife. Then they are to visit Inner-City Arts, an L.A. program that helps disadvantaged and homeless children through art. (The palace noted the duchess is "extremely interested in how the arts can help young people unlock their potential.")
On their final afternoon in the States, they are scheduled to attend an event for military veterans and their families at Sony Pictures Studios where they'll help put together care packages.
The Royal "Nontourage"
Prince William and Kate's philanthropic-focused itinerary and scaled-down entourage for their North American visit are a sign of the couple's determination to keep their royal life as modest as possible.
At home in England, Mr. and Mrs. Wales, as they prefer to be known, chose a small house in Anglesey, where William works, over Buckingham Palace as their primary residence, and resisted taking on butlers and servants.
Following their fairy tale wedding at London's Westminster Abbey on April 29, William returned to work as a search-and-rescue pilot in Anglesey, while Kate was seen grocery shopping for the couple herself.
Now on their first royal trip, and mindful of the recession, the duke and duchess "want to keep their entourage to a minimum," an aide told People magazine. So out with the lady-in-waiting. In with Middleton's hairdresser, James Pryce.
The 30-something hairdresser at London's Richard Ward Salon has been the Middleton family's stylist for seven years, and styled Kate's hair for both her wedding in April and her engagement last November. "She still comes into the salon and sits with everyone else -- there is no VIP area," a salon spokesperson told People.
Middleton may be asking Pryce for advice on her outfits as well, since she nixed bringing a dresser along. The duchess, whose wardrobe choices become instant best sellers, is reportedly bringing along 40 different outfit changes.
One area of help where the couple did not scrimp is media, bringing along a number of experts to help them handle the expected crush of press. They include press secretary Miguel Head, who has plenty of experience traveling with royalty, including William's first overseas tour when he represented Queen Elizabeth, and Patrick Harrison, the Prince of Wales's press secretary, who is an old hand at North American travel, having toured Canada with William's father, Prince Charles, and his wife, Camilla.
Helping the young royals navigate proper protocol during their trip will be their private secretary, Jamie Lowther-Pinkerton, a former army officer, and his assistant, Chris Kealey, who will act as the tour coordinator to keep the couple on schedule.
Sir David Manning, a former foreign policy aide to Prime Minister Tony Blair and Britain's ambassador to America for four years, will also tag along, coaching the couple on charity work, official functions and more.
ABC News' Luchina Fisher contributed to this story.