Simmonds, from Aldridge. is poised for her fourth successive Games having already won eight medals, including five golds.
She will join archer John Stubbs, Paralympic champion in the individual compound event at Beijing 2008 and also claimed silver in the team compound at Rio 2016. The pair will lead team-mates into the Olympic Stadium in the Japanese capital today, with 12 days of action scheduled to begin the following day.
Simmonds, 26 is Great Britain’s first female flagbearer at a summer Paralympics since fellow swimmer Maggie McEleny in 2000.
“I’m hugely honoured to carry the flag for the ParalympicsGB team – on behalf of all the athletes, support staff and for the entire nation back home,” she said in a statement.
“Just to be here in Tokyo is amazing but to carry the flag is the icing on the cake and I can’t wait for the competition to start.”
At the age of 56, Stubbs is the oldest athlete on the ParalympicsGB team. He said: “I felt incredibly emotional when I was told the news. For any elite athlete to go to the Games and be bestowed this honour is a privilege. Words can’t describe what it means to me.
“It’s been a torrid year - unfortunately I lost my Dad in January. He was my biggest fan, and hopefully if he’s looking down on me, he’s there saying: ‘Do it for the Stubbs family John, you’ve earned it and you deserve it’. I know my family will be as proud as punch.” Chef de mission Penny Briscoe said: “Both Ellie and John exemplify what it means to be a ParalympicsGB athlete.”