The Vitality Blast will begin in early June, with Finals Day at Edgbaston set for September 18, while the Royal London Cup is to return in July and August, as the ECB plots the resumption of a more recognisable county summer for 2021.
Last year, a truncated Blast was staged in September, with Finals Day pushed back into October - and consequently suffering the first washout in the competition's history - due to the impact of the Covid-19 pandemic. However, confirmation of the return to a 14-match group stage starting on June 9, followed by quarter-finals in late August, has come with the ECB's release of T20 and 50-over fixtures.
Nottinghamshire, who won the 2020 Blast after an 11-over semi-final and 16-over final on the reserve day at Edgbaston, will begin their defence against Worcestershire at New Road in a televised game. Sky Sports will show fixtures on each of the first four nights of the competition.
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Almost all of last season's cricket was held behind closed doors but the ECB remains hopeful of crowds being able to return this summer, while stressing that the "health and safety of anyone attending matches will remain the priority".
The Royal London Cup was scrapped altogether in 2020, and will return in the form of a "development" competition running alongside the inaugural edition of the Hundred (the schedule of which is yet to be confirmed). The 50-over cup will feature Groups A and B, which were drawn at random, for a three-week group stage starting on July 22, with the final held at Trent Bridge on Thursday, August 19.
Somerset remain the Royal London Cup holders, having won the last 50-over final to be played at Lord's in 2019.
The ECB has also unveiled plans to stage a number of warm-up matches ahead of the Royal London Cup between first-class counties and the national counties (formerly known as the minor counties) - fixtures that will see Somerset play games against Devon and Cornwall, Yorkshire take on Northumberland, and Middlesex face Hertfordshire, among others.
The programme for the regional women's 50-over and T20 competitions is due to be announced in the coming weeks.
"The stage is set for an exciting and important summer of domestic cricket for the First-Class Counties and the women's regional teams," ECB managing director of county cricket, Neil Snowball, said. "I know how much county members and supporters eagerly anticipate the release of fixtures and I am pleased that we have been able to plan a complete schedule for men's and women's cricket.
"The Vitality Blast has established itself as a much-loved tournament while the return of the Royal London Cup, alongside the remodelled County Championship for this season, will be warmly welcomed as we all look forward to the summer.
"I am also delighted that we will shortly release the schedule for the women's Regional 50-over and T20 competitions. These competitions will not only showcase the deepening pool of talent in women's cricket, but also further strengthen the professional pathway for our female players."
Full Vitality Blast and Royal London Cup fixtures
Royal London Cup groups
Group A: Essex, Worcestershire, Sussex, Middlesex, Kent, Durham, Gloucestershire, Hampshire, Lancashire
Group B: Leicestershire, Derbyshire, Glamorgan, Yorkshire, Surrey, Warwickshire, Nottinghamshire, Northamptonshire, Somerset