The reality TV star, 26, who is already mother to son Santiago, gave birth to the identical twins on May 22.
The babies are her first with Premier League footballer Jarrod Bowen.
Sharing a string of photographs of the girls, the daughter of EastEnders actor Danny Dyer wrote on Instagram: “Summer & Star. Our first week together & enjoying every moment of the newborn bubble.
“It’s been amazing watching santi be a big brother he has melted my heart in ways I couldn’t imagine and he just feels like such a big boy all of a sudden.
“My heart feels so so full and so excited for our journey together as a family of 5.”
One images shows one baby in a vest emblazoned with the words: “I’m Summer. That’s my sister Star,” while the other wears one saying: “I’m Star. That’s my sister Summer.”
Other photographs show the babies being cuddled by their parents Dani and Jarrod, 26, big brother Santiago, two, and grandfather Danny Dyer, 45.
Dyer shares Santiago with former partner Sammy Kimmence.
We need your consent to load this Social Media content. We use a number of different Social Media outlets to manage extra content that can set cookies on your device and collect data about your activity.
She dated Kimmence before she appeared on Love Island and later rekindled their romance after her split from Jack Fincham.
Dyer later separated from Kimmence, who was jailed for three and a half years in 2021 for defrauding two pensioners out of more than £34,000.
She has also starred alongside her soap actor father on a number of shows and they co-host a podcast, Sorted With The Dyers.
In 2021, Dani made an appearance on EastEnders as a pregnant taxi driver, Jeanette, who picked up Danny’s character from Albert Square.