The 92-year-old monarch has a busy week ahead, marked by a visit from US President Donald Trump in Windsor on Friday.
Meghan was christened and confirmed in the oak-panelled Chapel Royal by the archbishop, who also married her and Harry in May.
Prince William and the former Kate Middleton were joined at the christening by both of their families.
Baby found buried alive in Missoula County mountains
Authorities soon learned that a 5-month-old baby, who had been left in Crowley's care, had been missing for several hours. Eventually, Crowley told the deputies the infant was possibly buried somewhere in the mountains, Bassett said.
Welby, who will baptise the baby by pouring holy water from the River Jordan over his head, said the event would be "very nerve-wracking" but "a great privilege".
The Middleton family was also represented, with Louis'pregnant aunt, Pippa Middleton Matthews, at the intimate gathering. Once the ceremony is complete, guests will attend a private reception at nearby ClarenceHouse where they will be served cake taken from a tier of William and Kate's wedding cake.
Eleven-week-old Louis was dressed in the cream, frilly lace royal christening gown - a replica of the intricate robe made for Queen Victoria's eldest daughter in 1841.
After being worn by 62 royal babies, including Queen Elizabeth II and Prince William, the gown was deemed too fragile to wear, so a replica was created to continue the tradition.
Croatia identify England danger man for semi-final
JOHN STONES says a proven strength in adversity has united the England squad ahead of their World Cup semi-final against Croatia . These guys are a couple of games away from being immortalised, I bet they can't wait for the next game to start.
Prince Charles and his wife Camilla will be in attendance alongside Carole and MichaelMiddleton.
It's days like today that make being a mom so special for Kate Middleton.
The three-year-old had a clear message for paparazzi as she left Prince Louis' christening to go to afternoon tea: "You're not coming".
It's also where the coffin of Diana, Princess of Wales laid for a week before her burial.
Nicholas van Cutsem is the brother of William van Cutsem who was selected as a godparent for Prince George.
Boris Johnson resigns as British foreign secretary
Davis, for his part, insisted that May's position as prime minister is still safe. "I don't think it's a survival issue at all". The British government says Foreign Secretary Boris Johnson has resigned, amid a widening split in the Cabinet over Brexit .
Who is Brett Kavanaugh, Donald Trump's Supreme Court nominee?
The Times also reported that McConnell did not "want to draw the ire" of Paul over Kavanaugh's role in crafting Bush-era policies. Kavanaugh spoke at a University of Minnesota Law School event in 2008 and later published an article about the event.
IHOP acknowledges it faked IHOb name change
IHOP's "word of mouth" score skyrocketed following the name change, according to YouGov BrandIndex data . The change drew massive backlash on social media with some calling the move an " epic failure ".
McConnell calls Kavanaugh a ‘superb’ court pick
It may not also be his last, with liberal Justices Ruth Bader Ginsburg 85-years-old and Stephen Breyer turning 80 next month. Brett's mother Martha Gamble served as a Maryland state Circuit Court Judge from 1995 to 2001.
Rockets reportedly 'determined' to sign Carmelo Anthony
The 31-year-old averaged 7.5 points, 3.0 rebounds and 1.2 steals in 25.6 minutes per game across 61 games (15 starts) in Houston . The moves add to uncertainty for the Rockets around Swiss free agent center Clint Capela , who has not agreed to a new deal.
Death Toll Exceeds 100 After Heavy Rainfall Slams Japan
A man and his wife protect their home from water with sand bags in Saka, Hiroshima prefecture. "I've lived here for 40 years". Local government officials said pumping trucks were being deployed to help restore access to some of the worst-hit areas.
Wilshere snapped up by West Ham
Michail Antonio is one of three players West Ham United are prepared to offload if the right offer is made, according to a report.
England fans celebrate World Cup win over Sweden at IKEA
The Spurs right-back has been one of the key men in the squad as Gareth Southgate's side have reached the World Cup semi-final. The Euro '96 anthem managed to topple Drake from the top spot, clocking up over one million streams in just one day.