The actress has shared the baby news while thanking the "heroes", who helped her welcome her second child during the coronavirus outbreak.
Rauch went into labour without her husband, Winston Beigel, by her side due to hospital restrictions, and took to Instagram on Monday, May 04, to share her experience.
"I am incredibly thankful and overjoyed to announce the birth of our son, Brooks Rauch, who we just welcomed into the world and directly into our hearts," she wrote. "His arrival was made possible, in no small part, by the front line heroes - the nurses and doctors who show up each day to make sure that life keeps marching forward, regardless of the circumstances."
She added, "Words can't describe how grateful I am to have this baby boy join our family, but to say that it is a surreal time to be bringing life into the world is an understatement."
Rauch, who welcomed daughter Sadie in December 2017 after suffering a miscarriage, also touched on her past struggles.
"As I've previously shared, I am no stranger to loss on the road to motherhood - so to those dealing with infertility or grieving a loss, please know you are in my heart and I'm sending you so much love," she added.
Rauch also detailed her experience in an essay for Glamour, in which she described giving birth without her husband by her side.
"All I wanted was someone holding my hand, and by my side," she wrote. "The anxiety over giving birth without an advocate and support system in tow, compounded with the exposure concerns of walking into a hospital during a pandemic, were a lot to process."