Analysts had expected a revenue increase of 3.4 percent at stores open at least a year, according to a survey by Thomson Reuters.
The comparison covered the five weeks ended Dec. 29 and is considered a good indication of retail health as it excludes results from stores opened or closed in the past year.
Nordstrom shares rose $1.37, or 2.6 percent, to $55 in morning trading. Its shares have traded in a range of $46.27 to $58.44,
Overall revenue for December totaled $1.72 billion, up 9.4 percent from the same month in 2011.
The Seattle-based department store operator said sales were particularly strong in the last week of the season, as shoppers got a full weekend before Christmas, which fell on a Tuesday.
Children's and women's clothing and handbags were among the strongest categories, the company said. Sales were strongest in the Midwest and South.
For the first 11 months of Nordstrom's fiscal year, revenue was $10.81 billion, up 10.2 percent from a year ago, and revenue at stores open at least a year were up 7 percent.
Nordstrom has about 240 stores including 117 department stores and 119 Nordstrom Rack outlet locations.