T20 Blast champions Notts Outlaws will begin their defence of the title at Worcestershire Rapids on 9 June.
The England and Wales Cricket Board has confirmed fixtures for both limited-overs county competitions, with the 50-over One-Day Cup also returning.
Somerset last lifted the trophy at Lord’s in 2019, but Trent Bridge will host this summer’s final on Thursday 19 August, not the traditional Saturday.
The competition was postponed for the shortened 2020 season due to Covid-19.
Both sets of fixtures have been released before the schedule for The Hundred is confirmed.
The eight-team city-based 100-ball competition has been delayed by a year due to the coronavirus pandemic – it had been due to take place between 17 July and 15 August last year.
It means The Hundred and One-Day Cup group stages will run simultaneously, with counties having to rely on younger members of their squads for the latter.
The T20 Blast will return to a 14-match group stage split between North and South groups after it was reduced to a three groups of six last summer.
Edgbaston will once again host finals day on Saturday, 18 September, and is already a sell-out after ticket holders from last season were given the option roll their purchases over.
All T20 Blast and One-Day Cup fixtures will be available via BBC local radio stations with extensive coverage also on available on BBC Radio 5 Live Sports Extra.
The One-Day Cup opens with five fixtures on 22 July before Somerset begin their defence against Derbyshire on 25 July.
It will also be preceded by 20 matches between first-class counties and National Counties (previously known as minor counties) between 20 and 22 July.
The revamped County Championship season will begin on 8 April.
Fixtures for women’s domestic cricket, which will include regional 50-over and T20 competitions, in addition to The Hundred, are expected to be confirmed shortly.
Forty-one female players have signed professional domestic contracts to further establish the elite pathway for female cricketers.
T20 Blast groups
North: Durham, Lancashire Lightning, Yorkshire Vikings, Notts Outlaws, Worcestershire Rapids, Birmingham Bears, Derbyshire Falcons, Leicestershire Foxes, Northamptonshire Steelbacks
South: Hampshire, Sussex Sharks, Kent Spitfires, Essex Eagles, Middlesex, Surrey, Glamorgan, Somerset, Gloucestershire
Group Stage: 9 June-18 July.
Opening fixtures: Kent v Hampshire, Lancashire v Derbyshire, Worcestershire v Notts Outlaws, Somerset v Essex.
Quarter-finals: 24-27 August. Finals day: 18 September
One-Day Cup groups
Group A: Essex, Worcestershire, Sussex, Middlesex, Kent, Durham, Gloucestershire, Hampshire, Lancashire
Group B: Leicestershire, Derbyshire, Glamorgan, Yorkshire, Surrey, Warwickshire, Nottinghamshire, Northamptonshire, Somerset
Group Stage: 22 July-12 August.
Opening fixtures: Glamorgan v Warwickshire, Hampshire v Essex, Kent v Durham, Leicestershire v Derbyshire, Yorkshire v Surrey, Lancashire v Sussex.
Quarter-finals: 14 August; Semi-finals: 17 August; Final: 19 August at Trent Bridge