The Duchess's half-sister later appeared on "Good Morning Britain" to defend her Twitter outbursts, saying that she is entitled to talk about her relatives - and that no one would turn down a pay check.
The Duchess of Sussex stepped out on Saturday to attend Prince Harry's bff Charlie van Straubenzee's wedding to Daisy Jenks.
The prince, wearing a tailcoat and sunglasses, arrived with other groomsmen at the medieval church of St. Mary the Virgin in Frensham, 40 miles (64 kilometers) southwest of London.
She looked regal in a pleated navy shirt dress that she paired with a stand-out Philip Treacy fascinator and Aquazzura pumps.
Meghan was photographed chatting several guests at the wedding including Princess Diana's niece Celia McCorquodale and her husband George Woodhouse, pictured up top.
Samantha and Meghan haven't been in contact for years - but that hasn't stopped the Duchess's sister from weighing in on Meghan's life.
For Meghan's previous birthdays, she would often share snaps of her celebrations on her personal Instagram account, which has now been deleted. Meghan has been pushing the fashion boundaries ever since becoming the Duchess of Sussex.
"Harry is a wuss to allow the Duchess of Nonsense to mistreat everyone who has been close to her, especially her family".
Thousands of royal fans also took the opportunity to wish Meghan a happy birthday, and one said: "Happy birthday Meghan!"
Prince Harry served as best man for Straubenzee's wedding today, which explains the cards he's holding while he and Meghan walk together to the ceremony. Enough is enough. Act like a humanitarian act like a woman!
What do you think of Meghan's family's outbursts?
Meghan pointed to the product range and said, "I'm sure at some point we'll need the whole [lot]". "And hopefully we'll start a family in the near future".