Getting From Keflavik to Reykjavik Rental

There is a flybus+ option that will drop you at various hotels in Reykjavik. When you select ”book now”, you will see a dropdown list with a long list of hotels. If you know which hotel is near your airbnb, you could use that option.
https://www.re.is/tour/flybus/

Just to clarify, the Flybus generally is a large bus from the airport to the main bus terminal in Reykjavik. Depending on where you're going, you will normally be redirected to a smaller shuttle type bus to take you to your destination. The folks at the bus terminal are always very helpful if you are unsure of where to transfer.

Take the Flybus to the main bus terminal, then get a taxi to your accomodations. Reykjavik isn't that big.

It would be easier to give you advice if you told us where you want to go.

We took the flybus directly to our hotel. The next day the rental car company came and picked my husband up from the hotel where he completed the rental docs and then drove back to the hotel to pick me up. I would look to see where the flybus does drop offs besides the main bus terminal. And perhaps the rental company offers a hotel pick up. Edited to add that we used Blue Car Rental and they couldn’t have been more accommodating. I think the flybus main terminal may have a shuttle to the car rental as well.

Flybus is easy and not expensive. With large suitcases though, you might consider a taxi just for ease. We did that on one trip, from our hotel in Reykjavik back to KEF. That was Feb 2022 and it ran us $120 US dollars. I am sure it is a bit more now, but you get the general cost. That would be door to door service, so very convenient.

I used the Flybus+ to get to and from my hotel and it couldn't have been easier. Get the Flybus at airport, transfer to a smaller shuttle at the main bus station, and get off at the stop closest to your rental. As Laura noted you would pick the stop for a hotel that is closest to your rental. This page lists the main stops and the hotels closest to them, and there's a link there to a Google Map with the stops plotted on it: https://www.re.is/pick-up-locations/

What time does your flight arrive? If coming from the USA, chances are you'll be there early morning. It takes 45-ish minutes to get from the airport to the bus station, then it takes time for the shuttle bus to run its route. But depending on when your flight arrives, this still could be very early for your rental check in. My hotel stored my luggage, but I still had about 4 hours to kill before checking in. Since you mentioned large suitcases, that might be something to fold in to your plans.

The plan for now is to use FlyBus to get us to a hotel close to our rental and walk. I'm just wondering how persnickety the hotel might get when we get off the bus and we tell them we aren't staying there. It sounds like taxis are quite pricey so we are looking into alternatives.

The flybus doesn't necessarily stop at hotels. The stops are on the street. People will be getting off at each stop for numerous hotels.

If you tell us where you are staying we can help. Certain areas of Reykjavik can be hilly.