As it prepares for an expected IPO, Airbnb is stepping up its assault on the hotel industry.

The home-sharing juggernaut is acquiring a popular hotel-booking app, HotelTonight, which specializes in last-minute bookings at boutique and independent hotels. It's the most direct push into the hotel industry to date for Airbnb, which boasts 6 million listings worldwide and a $31 billion valuation.

A woman lounging by a hotel pool

Image source: Getty Images.

"A big part of building an end-to-end travel platform is serving every guest, whether they plan their trip a year or a day in advance," said Airbnb CEO Brian Chesky. "Working with the incredible team at HotelTonight, we will offer guests an unparalleled last-minute travel experience that provides unique, memorable hospitality on every trip, on any schedule, at any time."

The deal seems to signal that, while Airbnb has a number of advantages over traditional hotels, it is not as well-suited to last-minute bookings, especially late at night, as hosts need to be prepared for a guest's arrival and homes are often booked ahead of time. The acquisition builds on Airbnb's embrace of boutique hotels, as the company has worked over the past year to make it easier for such properties to list on its platform. Airbnb now boasts at least 15,000 boutique hotel options.

Finally, the move recognizes that staying in someone's home isn't the best fit for every guest. Acquiring HotelTonight will give Airbnb access to consumers who prefer a hotel experience and brings them onto its platform, perhaps making those guests more likely to consider staying in someone's home.

Terms of the deal were not disclosed. In its last funding round in 2017, HotelTonight was valued at about $460 million. Its app and website will continue to operate as a stand-alone business. Airbnb did not say how many listings HotelTonight would add to its platform.