Its Capital Connect franchise was extended by six months and its TransPennine Express contract by 10 months.
FirstGroup chief executive Tim O'Toole said: "Public transport is a key enabler of economic growth and the private sector is best placed to deliver high quality and attractive services that represent value for passengers and taxpayers and provide an economic return for shareholders."
He said he is "satisfied" with the company's turnaround so far and it is trading in line with expectations, but there remains "significant work" to be done.
Under the London bus asset sale, five depots in at Alperton, Greenford, Hayes, Uxbridge and Willesden Junction, along with 494 vehicles and 1,700 staff, will transfer to Metroline for £57.5 million.
Another three London bus depots Atlas Road, Lea Interchange and Westbourne Park, along with 400 vehicles and 1,500 staff, will transfer to Australian operator Transit Systems Group for £21.3 million.
FirstGroup's UK bus managing director Giles Fearnley said: "Our strategy is to focus on those areas of the country which offer the greatest potential and while we have been a key operator in London for many years, our focus going forward is on the deregulated market outside of the capital."