The Curly Sue star delivered baby boy Mason Blase Autenrieth, who weighed in at seven pounds (3.2 kilograms).
She kept her Twitter.com followers updated before going into labour, writing, "Hour 16. No baby. He's prob (probably) changing his outfit 400 times like his mother... Mason is tardy for the party."
The new arrival is the first child for Porter and her husband Brian Autenrieth, who she married in March (12).
The Curly Sue actress was joined by 50 guests, including her mum Laura Weiner and her younger sister Jordana, at the backyard bash in Agoura Hills.
She tells People.com, "It was a perfect day. I couldn't have imagined anything more beautiful. There was so much love and I can't wait for everyone to share it with our son!"
Porter and her husband Brian Autenrieth, who wed in March (12), are due to welcome their first child together in July (12) and they've already picked out the tot's name - they plan to call him Mason.
"So many Braxton Hicks. I've drank. I've bathed. I've excercise (sic) balled. I've swam. Can't catch a break. Chest gets tight! ready to push!" Former child star Alisan Porter is eager for her baby to arrive.
The Curly Sue actress, who is expecting her first child this summer (12), wed her partner Brian Autenrieth on Saturday (10Mar12).
The couple exchanged vows in front of 100 guests at a ranch in the mountains of Santa Monica and she later took to her Twitter.com page to post photos of herself in her bridal gown.
She tweeted, "I'm married!!!!!!"
Porter also told People.com, "We've been friends for 13 years and it's the most incredible feeling to know you're marrying your best friend."
The actress, best known for playing the title role in hit 1991 comedy Curly Sue, is expecting her first child, due in the summer (12).
Porter took to her Twitter.com page to share her happy news on Monday (01Jan12), uploading a snap of multiple pregnancy tests confirming she's expecting, as well as an ultrasound scan of the baby.
She tweeted, "Best thing about 2012, I'm gonna be a Mommy!!!!"