Cardoza, 53, had previously announced he would leave Congress after this year, but moved up his departure effective at midnight Wednesday for personal reasons, The Sacramento Bee reported
"In light of the fact that nothing is going to happen for the rest of the year, and in light of the fact that [my wife] and I are facing increasing parenting challenges, this seemed the right time to make this move," Cardoza told the newspaper in a Monday interview published Tuesday.
The Bee noted Cardoza and his wife, Dr. Kathleen McLoughlin, have a biological daughter and two adopted children.
"The real honor of serving in Congress is not working in historic buildings, but in laboring with so many unbelievably talented and dedicated individuals who serve our nation daily," Cardoza said in a later statement.
The Bee said no special election would be held to fill Cardoza's seat, now one of five that are vacant in the House. The others were held by Republicans Thaddeus McCotter of Michigan and Geoff Davis of Kentucky, and Democrats Jay Inslee of Washington and the late Donald Payne of New Jersey.
The Hill reported the five-term congressman gave a shout-out to the Blue Dog Coalition of more conservative Democratic House members.
Cardoza thanked his staff and several lawmakers, including Speaker John Boehner (R-Ohio) and House Minority Leader Nancy Pelosi (D-Calif.), giving a special thanks to the Blue Dog Coalition, saying "Long may you bark."
2014: NFL Cheerleaders [PHOTOS]
Mayor of L.A. suburb shot, killed inside home