Already this holiday season, a record $110.6 billion has been spent online, an increase of nearly 18 percent from a year ago, according to a new report.

The surge in internet spending comes as retailers such as Target and Walmart have been investing in their websites, adding more convenient delivery options or dropping shipping fees altogether. Traffic at stores, meanwhile, has been slightly lighter, with more consumers turning to their smartphones from their sofas to shop deals.

By this time last year, $93.9 billion had been spent online since Nov. 1, said Adobe Analytics, which tracks the web transactions of 80 of the top 100 internet retailers in the U.S.

"Weary holiday shoppers continue to look for alternatives to crowded stores, long lines and empty shelves in the final push to Christmas," said Taylor Schreiner, director of Adobe Digital Insights. "Retailers who can offer the easiest shopping experience, whether through excellent use of data to anticipate shoppers' needs or by providing an option for picking up products at brick-and-mortar stores, are the ones people are flocking to this week."

Adobe said mobile transactions this holiday season have so far reached $33.3 billion, up 57 percent from a year ago. It said "click-and-collect" orders, where shoppers make purchases online and then pick items up at stores, were up 47 percent from a year ago, making it the biggest "buy online pick up in store" Christmas on record.

Adobe is predicting online sales this holiday season, from Nov. 1 to Dec. 31, will reach at least $126 billion.