Members of the Rail, Maritime and Transport union (RMT) will hold a 24-hour strike as part of their long-running fight over jobs and pensions.
The strike will take place on Friday 19 August and will see only a fifth of normal services running - with half of lines seeing no service at all.
Overground workers employed by Arriva Rail London will stage a separate walk-out on the same day.
More than 1,600 London bus drivers are set to take strike action in a dispute over pay.
About 10,000 Tube workers and 400 Overground workers are to walk out.
The strike will last all day, causing significant disruption for commuters.
What are the other strike dates?
Two further days of rail strikes had already been announced by the RMT for 18 and 20 August.
Here are the train operators striking in August.
Thursday 18 and Saturday 20 August:
- RMT members will go on strike again.
- Avanti West Coast
- Chiltern Railways
- Cross Country Trains
- East Midlands Railway
- Gatwick Express
- Great Western Railway
- Greater Anglia
- Northern Trains
- South Western Railway
- West Midlands Trains
- TransPennine Express
- London Underground (19 August)
When is the bus strike?
Bus drivers, who are members of the Unite union and employees of London United, are set to strike on Friday 19 August and Saturday 20 August.
The strike will include workers based at Fulwell, Hounslow, Hounslow Heath, Park Royal, Shepherd’s Bush, Stamford Brook, and Tolworth depots.
The union said strike action was a result of the company offering a pay increase of 3.6% in 2022 and 4.2% next year.
It described the company’s pay increase offer as a real terms pay cut because of the soaring rate of inflation.
Why is there a Tube strike?
The union said that the new London Underground strike had been prompted by Transport for London’s (TfL) refusal to share details of a draft government proposal it received regarding funding of the capital’s transport system.
RMT general secretary Mick Lynch said: "Our members will once again take to picket lines in this important dispute over pensions, jobs and conditions.
"They have been messed around by TfL and Mayor Sadiq Khan.”
He added: “And to add insult to injury, they have not seen the detail of this funding letter from government.
"Unless there can be assurances made about jobs, pensions and detrimental changes to working conditions, then our strike on 19 August will go ahead."
The union said it would give TfL until 2 August to give these assurances.
What has Transport for London said?
Meanwhile, Andy Lord, TfL chief operating officer, said it had not yet received official notification of the strike action.
He said: "No agreement has been reached with the government.
"We continue to work closely with our unions, while at the same time talking to the government to try to ensure that any funding agreement is fair and is the right one for London’s recovery and for our colleagues.”
Mr Lord added: "There is significant work yet to be done.
“We urge the RMT to call off this action and work with us to support London’s recovery."