The Transformers actress gave birth to the baby boy on 13th February - just in time to make him the best Valentine's Day present ever for her 90210 husband!
Megan, 27, and Brian, 40, are already expert parents to sons Noah, 1, and Kassius, 12, who is Brian’s son from a previous relationship.
The duo are reportedly thrilled to have another child, although a name for the little bundle of joy has yet to be released.
And, while the mum-of-two kept relatively quiet about her pregnancy, Brian told a US gossip site back in September 2013 that the actress was taking motherhood in her stride.
“She is doing great, she did great the first time around. But I wouldn’t wish the experience on anybody, I couldn’t do it! I couldn’t make a baby. It is unbelievable!
“I do whatever she asks for and I say ‘Yes’ no matter it may be.”
It's nice to hear that he's such a doting husband, isn't it?
Congratulations to the couple - we bet Kassius and Noah will be very excited to hear that they have a new baby brother.