This is the tenth British royal baby born this century, including the queen's seven other great-grandchildren and her two youngest grandchildren.
Here's a look at 50 years of royal babies around the world.
Prince Harry and Meghan, Duchess of Sussex, named their firstborn son Archie Harrison Mountbatten-Windsor. They made their first public appearance with baby Archie in St. George's Hall at Windsor Castle on May 8, 2019, two days after his birth.
On July 23, 2013, a crowd gathered outside of St Mary's Hospital in London to greet the day-old Prince George, first son of Prince William and Catherine, Duchess of Cambridge. Prince George is third in line for the British throne.
Checking out butterflies
Just before his first birthday, in 2014, Prince George and his parents visited the butterfly exhibit at the Natural History Museum in London.
Princess Charlotte's christening
Prince William and Catherine welcomed their second child, Princess Charlotte, in 2015. Here she is at 2 months old at her christening ceremony.
A 16-month-old Princess Charlotte and her 3-year-old brother Prince George, were entertained by a balloon artist while touring Canada in 2016.
And in 2017, Princess Charlotte and Prince George accompanied their parents on a three-day trip to Germany.
Introducing Prince Louis
William and Catherine's third child, Prince Louis of Cambridge, was just a few hours old when this picture was taken outside of St Mary's Hospital in London on April 23, 2018.
Christening Of Prince Louis
Prince Louis was christened in July 2018 at St James's Palace in London.
William's first Christmas
Prince William was 6 months old when he posed for holiday photos with his mom, Princess Diana, at Kensington Palace in 1982.
Two princes for Christmas
New dad Prince Charles got in on the holiday fun as well.
Prince Harry's debut
In this photo, Prince Charles and Princess Diana introduce a 1-day-old Prince Harry.
A family portrait
Three weeks later, in October 1984, the newborn Prince Harry posed with mom, dad and older brother Prince William, age 2.
A very royal vacation
In 1986, the British Royal family visited the Spanish royals in their summer home in Palma de Mallorca, Spain. King Juan Carlos can be seen here talking to 2-year-old Prince Harry.
Prince Harry with a royal dog
Here, Prince Charles lifts Prince Harry onto the back of Archy, King Juan Carlos' dog.
Princess Anne and family
In 1980, young Peter Phillips posed with parents Princess Anne and Captain Mark Phillips to commemorate the princess' 30th birthday.
Christening Princess Beatrice
In this photo, Andrew and Sarah, Duke and Duchess of York, carry their first daughter, Princess Beatrice, at her christening in 1988.
Princess Eugenie in white
Two years later, Princess Eugenie was born. Here she is at her christening in December 1990.
Beatrice and Eugenie visit Argentina
Princesses Beatrice and Eugenie accompanied their mom to Argentina during the summer of 1990.
... And Switzerland
Here, 1-year-old Princess Eugenie and older sister Princess Beatrice play soccer on the sidelines of a charity polo match in Mies, Switzerland.
Zara performs the sideways baby lift
In 2015, Queen Elizabeth's great-granddaughter Mia Tindall joined her mother, Zara Tindall, in cheering on dad as he competed in the Artemis Great Kindrochit Quadrathalon in 2015. Mia was 18 months old.
Meeting dad at the finish line
Mia congratulated her father, Mike Tindall, at the quadrathalon finish line.
A royal cheerleader
Two-year-old Mia also came along to support mom when Zara competed in the Badminton Horse Trials in the summer of 2016.
Playtime in the palace
In this 2003 photo, taken just a few weeks before her second birthday, Princess Aiko of Japan plays with her mom, Crown Princess Masako, at Togu Palace in Tokyo.
Family photo time
Princess Aiko's father, Crown Prince Naruhito, is the first son of the emperor and empress and first in line for the throne. Princess Aiko is not considered part of the line of succession because she is female.
Another Japanese princess
Princess Kako was born on December 29, 1994 to parents Prince Akishino and Princess Kiko. Princess Kako's father is the younger brother of the Crown Prince and second in line for the Japanese throne.
An imperial holiday
Princess Kiko and Prince Akishino welcomed a baby boy in September 2006. Here, the baby Prince Hisahito takes in the sights while vacationing at an imperial ranch north of Tokyo.
Baby's first photos
This photo, taken in 1968, was the among the first pictures of Denmark's Crown Prince Frederik. His mother is now the Queen of Denmark.
A sleepy future king
Crown Prince Frederik's first-born son made his public debut at 3 days old. He is named Christian, in accordance with a more than 450-year-old Danish tradition of alternating between Frederik and Christian as names for future kings.
A Danish princess
Crown Prince Frederik and his wife, Crown Princess Mary, welcomed a daughter in April 2007. Here is Princess Isabella Henrietta Ingrid Margrethe at her christening.
Christian and Isabella wave hello
In this photo, the Danish royal family waves from the balcony of Fredensborg Palace Church.
Little princes in Denmark
Danish Prince Joachim and his first wife, Princess Alexandra, play with their two children, Prince Felix and Prince Nicolai, in this 2002 photo.
A princely Christmas tree
And in 2009, Prince Joachim and his second wife, Princess Marie, took their son Prince Henrik to see a Christmas tree lighting.
In 2011, Crown Prince Frederik and Princess Mary welcomed twins, Prince Vincent and Princess Josephine. The twins were baptized in Copenhagen in April 2011.
A royal baby boom
Babies in tow, the Danish royal family gathered in Southern Jutland for a summer holiday in 2011.
This is the 2012 christening of Princess Athena Marguerite Françoise Marie in Moegeltoender, daughter of Danish Prince Joachim and Princess Marie. She was 5 months old.
A baby king
This baby grew up to be King of the Netherlands. Willem-Alexander, seen here as an 11-month-old prince, was crowned king in 2013.
In this photo, Prince Willem-Alexander practices his proclamation face.
By 1969, Prince Willem-Alexander had two younger brothers, Prince Johan Friso and Prince Constantijn.
Christening a princess
Crown Prince Willem-Alexander of the Netherlands holds his first-born daughter, Princess Catharina-Amalia, at her christening in 2004.
A new sister
Princess Catharina-Amalia sits on her father's shoulders while Princess Maxima carries the family's second daughter, Princess Alexia.
Meet Princess Alexia
Here's a closer look at the newborn Dutch Princess Alexia making her big debut.
All dressed up
Here are Princess Catharina-Amalia and Princess Alexia dressed to the nines at Alexia's christening.
A princess with personality
Princess Alexia watches her big sister ham it up for the camera in Buenos Aires in 2005.
Royals in the snow
The growing royal family took a vacation to a ski resort in Austria in 2006. Here they are posing in the snow.
A royal trifecta
And in 2007, the Dutch royal family welcomed a third daughter, Princess Ariane. This is a picture from her christening.
Happy birthday, Alexia
Princesses Ariane, Catharina-Amalia and Alexia all sat for this family photo on Alexia's second birthday.
Royal babies in Belgium
In this 2005 photo, the Belgian royal family introduces 2-day-old Prince Emmanuel. The prince is third in line for the Belgian throne, after his two older siblings.
In this 2005 photo, Princess Elisabeth, age 3, holds her new baby brother.
A royal adventure
The Belgian royal family enjoyed a summer day at a park in 2006.
Princess Eleonore, the youngest member of the Belgian royal family, was born in April, 2008. She was just one day old in this photo.
Photos at grandma's house
Princess Eleonore slept through this photo session at the Royal Palace in Laeken, Belgium, when she was 2 months old.
Princess Eleonore was two years old when the family went on this summer trip to a farm in Loppem, Belgium.
Introducing Princess Leonor
Week-old Princess Leonor of Spain slept through this photo session in Madrid in 2005.
Princess Leonor, big sister
This 2007 photo of Princess Leonor was taken just after the birth of her little sister, Sofia.
Princess Sofia of Spain was born on April 30, 2007. She was introduced for the first time four days later.
Ready for her close up
Much like her sister before her, the 4-day-old princess was sleeping at her media debut.
Sweden's royal family
Here is a baby photo of 2-week-old Crown Princess Victoria of Sweden with her parents, King Carl Gustaf and Queen Silvia.
Happy birthday, Victoria
King Carl Gustaf took this photo of Crown Princess Victoria on her first birthday in 1978.
Sweden's Prince Carl Philip
Princess Victoria was just shy of 2 years old when little brother Prince Carl Philip was born. Here is the baby prince on his christening day.
Three years later, in 1982, Princess Madeleine was born. Here she is at her christening. The princess is the youngest of King Carl Gustaf's three children.
Madeleine's first Christmas
This Christmas portrait was taken when Princess Madeleine was 6 months old.
Christening of Caroline Casiraghi
Princess Charlotte Casiraghi of Monaco, the granddaughter of Grace Kelly, was just a few weeks old when this photo was taken at her christening.
Princess Charlotte was 12 when her younger half-sister Princess Alexandra was born in 1999. Here is the baby princess being introduced to the citizens of Monaco from a palace balcony.