Robson, 24, joined Wasps from Gloucester Rugby last season and is in fine form, with six tries and six assists in his last seven Aviva Premiership games for the side.
"It was a really easy decision to re-sign," said Robson. "I'm loving my time here at Wasps and appreciate the confidence Dai [Young] has shown in me. I'm really enjoying the attacking brand of rugby we play and I feel my game has improved massively since I've been at Wasps."
Myall, 29, has racked up 74 appearances in black and gold since joining from Sale Sharks in 2013 and recently returned to action after recovering from a long-term knee injury.
"I am delighted to have signed a new deal with Wasps having really enjoyed my time here over the past four years," he said. "During that time, the club has grown from strength to strength and I'm excited to be part of what is happening at Wasps at the moment. We have some incredible players and a team of great coaches who I thoroughly enjoy working with."
Meanwhile, 24-year-old Young - son of Wasps director of rugby Dai Young - has penned a new deal after a season in which he scored six tries from 20 appearances.
"It was an easy decision to sign an extension at Wasps," he said. "I have really enjoyed my time at the club and feel like I have developed a lot as a player. I am very excited about the direction the club is moving in and the calibre of players we have got at Wasps is a massive draw. I feel like this is the right place for me to carry on developing."
Wasps are top of the Aviva Premiership table with five wins from five games so far this season.