The bus is one of the quickest and easiest ways to get to the Malaga city center. It costs 4 euros each way and you can pay by cash or card on the bus. Follow the signs for the bus A, you will go down an escalator outside and see the bus directly ahead. The bus takes roughly 20 minutes without traffic and makes multiple stops. 

There is a train that leaves from the airport to the city center in less than 15 minutes, the C1. The ticket costs 2 euros and it runs every 20 minutes. The last train leaves at 00:24h. 

A cab is the quickest way to get into the city, but also the most expensive. It takes 15 minutes without traffic to get into Malaga and will cost roughly 30 euros, depending on the time of day. It is more expensive at night and during rush hours. Follow the signs for taxis in the airport and you will see a line of taxis waiting.