The England white-ball skipper won't be ever-present for Middlesex, with Morgan's workload to be managed through a busy international summer
Stephen Eskinazi will captain Middlesex in the T20 Blast, taking over from Eoin Morgan, whose availability will be managed with his fitness in mind.
England have a busy white-ball summer, with series scheduled against the Netherlands, South Africa and India, before the T20 World Cup in the autumn.
Morgan is also set to captain London Spirit in The Hundred, reuniting with Trevor Bayliss, and he told Evening Standard that he has learnt from the quad injury suffered during the five-match T20I series against West Indies in January to not overburden himself with fixtures.
"I think it's important that I play it week by week to start with, and aim for the T20 World Cup," he said.
Therefore, he won't play back-to-back games for Middlesex, whose campaign begins on Thursday at Radlett against Gloucestershire. He will feature there, but not a day later when they travel to the Ageas Bowl to face Hampshire.
When present, Morgan is likely to bat at No.5, with Middlesex otherwise light on power-hitting through the middle and death overs.

Morgan won't be ever-present in 2022 for Middlesex (Alex Davidson/Getty Images)
Eskinazi, meanwhile, has been the county's best T20 cricketer for the last two years and can count himself unfortunate not to have a Hundred contract ahead of the tournament's second edition.
In 2020, he was the competition's second-highest run-scorer and last year finished eighth in the standings despite missing a couple of games due to injury.
He has returned to fitness following a month off with a fractured thumb suffered in the County Championship draw with Derbyshire, which he began with a century. His hundred against Essex in last season's Blast was just the second ever made at Lord's in T20 cricket.
Following visa delays, Mujeeb Ur Rahman won't arrive in London until after Afghanistan's series against Zimbabwe, with Australian off-spinner Chris Green available to Eskinazi from the start of the competition.