That marks a 16.8 percent increase from a year ago, and makes Monday the largest online shopping day in U.S. history.
Mobile also had a record day, Adobe found, saying smartphones have become the "de facto device" for on-the-go shopping. Mobile sales on Cyber Monday reached $2 billion for the first time.
"This year, mobile shopping was dominant both in the morning and afternoon, and desktop only staged a comeback in the evening when people were home," Taylor Schreiner, director of Adobe's Digital Insights division, said.
Adobe measures 80 percent of online transactions from 100 major U.S. retailers.
