The Little Mix singer gave birth to the couple's first child last month.
The Netflix series' fashion guru wrote that he was "fully obsessed" with his new son, who was born July 10 via a surrogate.
“Mom has the reproductive organs of a finely-tuned sports car, and in a flash raced this baby over the line just in time for kickoff.”
The actor and comedian revealed she was expecting just two weeks ago.
"A beautiful little blessing has chosen me to be her mother."
"Future best friends pending."
It is the US singer and British actor’s first child together.
The two went back and forth on Twitter over a mistake in the description of little X Æ A-12 Musk's moniker.
The TV presenter said he's 'head over heels'.