The Fall Out Boy bassist's girlfriend Meagan Camper gave birth to a baby boy named Saint Lazslo on Wednesday, 20 August.
A rep for the musician told Us Weekly magazine that Meagan and Saint were "happy and healthy" and that the whole family is "thrilled" by the new arrival.
Pete is already dad to son Bronx, five, from his marriage to Ashlee.
The 35-year-old was married to Jessica Simpson's younger sister, 29, from 2008 until 2011. They had been dating for two years before their marriage.
Ashlee is now engaged to Hunger Games actor Evan Ross, the son of singer Diana Ross.
Congrats to Pete and Meagan!
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Stars who welcomed babies in 2014:
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