The queen and her husband Prince Philip joined a congregation of hundreds for the 40-minute service at Fleet Street's St Bride's Church - regarded as the spiritual home of journalists worldwide - led by the rector Canon David Meara.
The royal couple were present at the original reconsecration ceremony at the Church of England church in December 1957, after the building had been repaired following extensive damage during World War II.
Following yesterday's service, the royal couple signed the Book of St Brides, before proceeding to a reception at nearby Bridewell Hall.
The Book of St Brides was the creation of the church's former rector, Reverend Canon John Oates, who wanted to start a memorial to remember those in the journalism industry who have lost their lives.
He said: 'In this place where the printed word first established itself, we remember all who write what many read and speak where many listen, especially those journalists, cameramen and support staff who have lost their lives in the pursuit of truth and to bring us the news.' At Bridewell Hall, the queen and prince spent time talking to senior figures in the journalism industry, including veteran journalist John Simpson, who discussed her recent official trip to Uganda with the monarch.
He said: 'We were talking about her trip and how it has changed over the years. We also talked a bit about Iraq. I told her how bad it is there and what lovely people the Iraqis are. 'She said she hoped that life gets a bit better for them soon.'