She went on to write that while his birthday was spent under NSW's strict lockdown restrictions, they found a way to make it memorable.
"A lockdown birthday that was made so special by his school teachers, little friends, Mums sending videos, FaceTime chats with cousins and beautiful family and even happy birthday sung to him by Aunty Lally and family from the front garden!
"So much love and kindness 🎈thanks to everyone who reached out today 🤗 it made me forget I have nine weeks regrowth," she added.
Emily’s co-stars were quick to send their well wishes in the comments, writing sweet words to both Henry and Emily.
"Oh Henry, happy happy 6th birthday darling. I know you would have had a brilliant day with your beautiful Mum and Lauren. Lots of love Hen," Georgie Parker wrote.
"Happy birthday Henry!! Many blessings:-))))," Ben Foster said.
Emily and her ex partner Paul Jackson welcomed Henry into the world on August 3 in 2015 after the actress underwent IVF. The couple separated a year later.
Emily previously spoke to TV WEEK about her fears as a mother, especially considering she had Henry "so late in life".
"Every day is a reminder of how you have to stay alive as long as possible," she told the publication.
"I'm really conscious of eating properly, exercising and looking after myself, to give myself the best possible chance of being there for his 40th birthday."