"The Queen and The Earl of Wessex [Prince Edward], today (Tuesday 17 May), visited Paddington Elizabeth line station to mark the completion of the new railway ahead of its opening to passengers on Tuesday 24 May," the statement read.
The queen then met with the line's staff, who will operate the railway, it added.
UK Prime Minister Boris Johnson along with London Mayor Sadiq Khan, UK Transport Secretary Grant Shapps, and other senior officials also attended the event, according to the statement.
This is the second time the Queen has visited the line, previously making an appearance there during its construction in 2016. Queen Elizabeth II became the first reigning monarch to travel on the London Underground in 1969, when the Victoria line was launched.
The construction started in 2009 and the line was due to open in 2018, but the process was delayed in 2019 due to rising construction costs before being relaunched in 2021. The line is set to connect Reading and Heathrow in the west, through central London, to Shenfield and Abbey Wood in the east.