The 39-year-old, who joined the ITV1 breakfast show in 1997, bowed out to front another ITV1 programme, Loose Women, full time.
McLean received applause as she presented her final bulletin this morning. She dressed in jeans and told viewers that it will be "cold and dark" tonight at midnight, but joked: "Tomorrow I won't care because I won't be doing this anymore."
The show's anchor Kate Garraway paid tribute to McLean, saying: "You light up the screen. Everybody loves you."
Earlier this month, Fiona Phillips presented her final GMTV show after quitting in August. Her replacement, Sky News presenter Emma Crosby, will take over in January.