It found shoppers spent nearly $6bn online on Monday through Friday last week, creating another record.
After hitting a record $1.25bn in sales on Cyber Monday, online sales on Tuesday and Wednesday also broke $1bn.
comScore says online sales are up 15% year-on-year to $18.7bn in November and the first two days of December.
Free shipping appears to be a big draw, applying to 63% of sales, up from 52% a year ago, it said.
"Consumers have come to expect free shipping during the Holiday promotion periods, and retailers, in turn, have realised that they must offer this incentive," said comScore chairman Gian Fulgoni.
Spending on items including clothing, general merchandise, toys and electronics and in department stores, rose 4.7% to $125bn in the October 30-November 26 period, according to MasterCard Advisor's SpendingPulse.
That includes online and brick & mortar store purchases.
