20 Fenchurch Street is a commercial skyscraper in London that takes its name from its address on Fenchurch Street, in the historic City of London financial district. It has been nicknamed "The Walkie-Talkie" because of its distinctive shape, said to resemble a two-way radio handset. Construction was completed in spring 2014, and the three-floor "sky garden" was opened in January 2015. The 38-storey building is 160 m (525 ft) tall. Since July 2017, the building has been owned by Lee Kum Kee Groups.

Designed by architect Rafael Viñoly and costing over £200 million, 20 Fenchurch Street features a highly distinctive top-heavy form which appears to burst upward and outward. The entrance floor and 34 floors of office space are topped by a large viewing deck. A bar and restaurants are included on the 35th, 36th and 37th floors; these are, with restrictions, open to the public.

The tower was originally proposed at nearly 200 m (656 ft) tall but its design was scaled down after concerns about its visual impact on the nearby St Paul's Cathedral and Tower of London. It was subsequently approved in 2006 with the revised height. Even after the height reduction there were continued concerns from heritage groups about its impact on the surrounding area. The Secretary of State for Communities and Local Government, Ruth Kelly, called in the project for another public inquiry. The project was consequently the subject of a public inquiry; in 2007 this ruled in the developers' favour and the building was granted full planning permission. In 2015 it was awarded the Carbuncle Cup for the worst new building in the UK in the previous 12 months.

In 2013 Paul Finch of the Design Council CABE said he regretted supporting the project during the public inquiry, saying that the developers "made a mess of it" and were architects of their own misfortune.