Stewart is England's most-capped cricketer; he played 133 Test matches and 170 One-day Internationals before retiring after the final Test of the 2003 series against South Africa.
Hussain represented England in 96 Test matches and 88 One-day Internationals; he retired from cricket after hitting a match-winning century against New Zealand at Lord's last May.
Commenting on the news, Stewart said: "It is an honour to be given this recognition by MCC. The Club is the most historic in the world, with a very proud tradition. I am delighted to have been given lifetime membership of MCC."
Hussain said: "I was thrilled to be made an Honorary Life Member. It is the greatest cricketing accolade I could receive.
"I loved everything about playing at Lord's; this will continue my involvement with the historic ground, and give me a long-term association with MCC."
MCC was once responsible for running all English cricket but gave up this role over 30 years ago. However the club remains responsible for the Laws of Cricket, the sport's rulebook.