The retailer saw like-for-like sales lift 5.1% in the six weeks to 2 January, but it relied on a 21.4% jump in online trade as comparable store sales dropped 1.2%.
The Partnership also revealed "challenging" trading at its Waitrose supermarket arm, which suffered a 1.4% fall in like-for-like sales excluding fuel over the six weeks.
Sir Charlie Mayfield, chairman of the John Lewis Partnership, said: "This has been a strong Christmas trading period for the partnership despite the non-food market seeing significant shifts in trade patterns and the grocery market continuing to be challenging."
The employee-owned firm, which runs 46 John Lewis stores, shrugged off the unusually mild December weather as it hailed "impressive" trading across fashion, home and technology.
This comes despite fears sparked for clothing retailers yesterday after Next posted a shock fall in its store sales and a sharp slowdown in its Directory catalogue and online arm, blaming the mild conditions in November and December.
John Lewis said the number of shoppers on the high street was lower this year as consumers continued to shift online, with trading through its website making up 40% of all sales in the six-week festive season.
But it saw so-called shopper footfall pick up as the clearance sales kicked off after Christmas, helping department store sales rise 23% in the week to 2 January.
Results for the Waitrose business confirmed the tough conditions in the supermarket sector as grocers battle amid a ferocious price war and the increasing might of discounters Aldi and Lidl.
The group said trading came late for the Waitrose chain, peaking with record trade on 23 and 24 December, while online sales rose 7.9% over the six-week period.
John Lewis said its overall festive performance has kept it on track with full-year profit expectations for between £270m and £320m, which comes against £342.7m the previous year.
John Lewis said the Black Friday shopping bonanza saw it send out 18% more parcels than a year earlier - peaking at five parcels a second in the busiest hour.
Sir Charlie said "significant" investment in the group's distribution and IT operations helped it cope with uneven trading over the Christmas season.
"Despite the fact trade was even more concentrated across a number of very busy shopping days, our operations performed especially well," he added.
Booming online business for the department store chain saw smartphone and tablet sales jump by nearly a third, while shoppers increasingly used its click and collect service - up 16% on a year earlier and now making up half of all orders.
John Lewis said 35% of all online orders were now collected from Waitrose branches.
Overall sales for the John Lewis Partnership lifted 4.1% year-on-year in the six weeks, to £1.8bn.
The department store saw sales rise 5.1% for home products, 6.1% across fashion and 9.6% in technology.
Andy Street, managing director of John Lewis, said its growth in fashion sales would have been even higher if the weather had not been so unusually mild.
"We won market share in fashion, quite decisively," he added.
He said footfall in stores fell as the warmer weather "didn't put people in the mood" for festive shopping trips.
"But people were also using the convenience of online," he said.
Menswear was its best-selling area in fashion, while Star Wars Lego sets were among its most popular toys.
John Lewis also saw strong demand for wearable technology, such as the Fitbit fitness tracker and Apple Watch.
Mark Price, managing director of Waitrose, said there was "no festive easing of the tough market conditions we've seen throughout 2015", with grocers buffeted by ongoing food price deflation.
But he said profits were maintained despite the sales drop thanks to keeping a tight lid on costs, while the group also saw good growth in online trading.