Defender Chico will link up with former Swans manager Michael Laudrup at defending champions Lekhwiya while Hernandez has joined Al-Arabi.
Chico told the Swansea website: “It feels like I am leaving my family. The club is special because everyone makes you feel good and welcome every single day.
"I have really enjoyed my time here. When we won the League Cup it was one of the best moments in my career. I will always follow Swansea’s results. I will not forget what this club has done for me."
Chico moved to south Wales for £2m two years ago from Malaga, where he had also worked under Laudrup.
Hernandez also arrived at the Liberty Stadium in 2012 for a then club-record fee of £5.5m.