She was given an Oyster card and shown how to use it on a ticket machine.
The Queen smiled warmly as she met Crossrail and Elizabeth line workers and walked slowly as she made her way around the station concourse.
Elizabeth line customer experience assistant Kofi Duah said he was “thrilled” to present an Oyster card to the Queen and show her how it could be topped up on a machine.
The Queen did not top up the card, which was pre-loaded with £5 of credit.
Crossrail, the project to build the new east-west railway, was delayed and over budget due to numerous issues including construction difficulties and complications installing signalling systems.
It was due to be completed in December 2018 and was set a budget of £14.8 billion in 2010.
The total cost has been estimated at £18.9 billion, including £5.1 billion from the Government.
The Elizabeth line will boost capacity and cut journey times for travel across the capital.
It will stretch from Reading, in Berkshire, and Heathrow Airport, in west London, to Shenfield, in Essex, and Abbey Wood, in south-east London.
Trains will initially operate in three sections, which are expected to be integrated in the autumn.
The Elizabeth line, named in honour of the Queen in her Jubilee year, will open to passengers on May 24.
. Queen Elizabeth II at Paddington station in London, to mark the completion of London's Crossrail project. Picture date: Tuesday May 17, 2022.
Queen Elizabeth II dressed in yellow at Paddington station in London, to mark the completion of London's Crossrail project. Photo: Andrew Matthews
. (Right to left) Prime Minister Boris Johnson with Transport Secretary Grant Shapps and Mayor of London Sadiq Khan on a Elizabeth Line train at Paddington station in London, to mark the completion of London's Crossrail project. Picture date: Tuesday May 17, 2022.
(Right to left) Prime Minister Boris Johnson with Transport Secretary Grant Shapps and Mayor of London Sadiq Khan on a Elizabeth Line train at Paddington station in London, to mark the completion of London's Crossrail project. Photo: Andrew Matthews
1. (Right to left) Prime Minister Boris Johnson with Transport Secretary Grant Shapps and Mayor of London Sadiq Khan on a Elizabeth Line train at Paddington station in London, to mark the completion of London's Crossrail project. Picture date: Tuesday May 17, 2022.
(Right to left) Prime Minister Boris Johnson with Transport Secretary Grant Shapps and Mayor of London Sadiq Khan on a Elizabeth Line train at Paddington station in London, to mark the completion of London's Crossrail project. Photo: Andrew Matthews
2. Queen Elizabeth II at Paddington station in London during a visit to mark the completion of London's Crossrail project. Picture date: Tuesday May 17, 2022.
Queen Elizabeth II at Paddington station in London during a visit to mark the completion of London's Crossrail project. Photo: Ian West
3. Queen Elizabeth II using a oyster card machine at Paddington station in London, to mark the completion of London's Crossrail project. Picture date: Tuesday May 17, 2022.
Queen Elizabeth II using a oyster card machine at Paddington station in London. Photo: Andrew Matthews
4. The Earl of Wessex uses an oyster card to go through barriers to ride on a Elizabeth Line train at Paddington station in London, to mark the completion of London's Crossrail project. Picture date: Tuesday May 17, 2022.
The Earl of Wessex uses an oyster card to go through barriers to ride on a Elizabeth Line train at Paddington station in London, to mark the completion of London's Crossrail project. Photo: Andrew Matthews