Former red-ball skipper Colin Ackermann will focus on the T20 team ahead of the Blast. Parkinson's tenure is expected to begin against Nottinghamshire in June
Leicestershire have installed Callum Parkinson as their new captain in the LV= Insurance County Championship, replacing Colin Ackermann.
Ackermann will remain the T20 captain ahead of the start of the Blast next week, with Lewis Hill already in place to lead in the One-Day Cup.
Parkinson, who has played 111 matches for Leicestershire across the formats including 42 first-class games, will start his tenure when the Championship resumes on June 12 against Nottinghamshire at Grace Road.
He has made an impressive start to the new Championship season, taking a dozen wickets and scoring 245 runs in 10 innings.
Last time out, a second-innings 45 went a long way to the Running Foxes securing a draw in the Division Two clash with Sussex.
"It is a huge honour to be appointed four-day captain and I’m incredibly grateful to the club for placing that faith in me," said the 25-year-old, who joined in 2017 from Derbyshire.

Colin Ackermann will continue to lead in the Blast (Tony Marshall/Getty Images)
"I have learned so much from Colin (Ackermann) during my time as vice-captain.
"I will continue to lean on him for advice, whilst implementing my own ideas and direction to win matches for Leicestershire.
"Personally, I feel I have matured massively over recent seasons and developed into a player that can help guide the club to success."
Director of cricket Claude Henderson added: "We have decided that now is the right time for a change and recognised Callum’s qualities (Parkinson) are ideally suited to leading the team in four-day cricket for the remainder of the season.
"Callum has been an inspiring voice in the changing room, and he commands huge respect through the way he approaches his cricket. We have full belief that he is the right man to take up the role."