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The Blackwall Tunnels are a pair of Tunnels on the A102 under the River Thames, linking the London Borough of Tower Hamlets on the north side with the Royal Borough of Greenwich on the south. The northern portal lies just south of the East India Dock Road (A13) in Blackwall; the southern entrances are just south of The O2 Arena on the Greenwich Peninsula. The road is managed by Transport for London (TfL).

The first tunnel was originally opened as a single bore in 1897 as a major transport project to improve commerce and trade in London's East End in an age before motor vehicles. As such it is designed for horse drawn traffic and includes a number of tight bends, reputedly to prevent horses seeing daylight in the distance. By the 1960s, traffic levels had reached the point where a second tunnel was required; this was built to the east of the original tunnel and to a more modern alignment. The new tunnel opened in 1967 and now carries southbound traffic, leaving the original tunnel to carry northbound traffic.

The northern approach takes traffic from the A12 and the southern approach takes traffic from the A2, making the tunnel crossing a key link for both local and longer-distance traffic between the north and south sides of the river. It forms part of a key route into Central London from South East London and Kent and is the easternmost free fixed road crossing of the Thames, and regularly suffers congestion.

The tunnels are no longer open to pedestrians, cyclists or other non-motorised traffic, and the northbound tunnel has a 4.0-metre height limit. One bus route runs through the tunnels.