The suspect was arrested in the port area of Dover in the Kent County in the southeast of England.
“We have made a significant arrest in our investigation this morning. Although we are pleased with the progress made, this investigation continues and the threat level remains at critical," Neil Basu, the Deputy Assistant Commissioner, Senior National Co-ordinator for Counter Terrorism Policing said.
Basu stressed that the arrest would be followed by further actions by the police, providing no additional details on the issue.
On Friday, an explosion, most likely involving an improvised explosive device, hit the tube station, causing facial burns to the passengers. London police said that they regarded the blast as a "terrorist incident."
Following the attack, media reported, citing sources, that the police had identified the suspect behind the attack with the help of CCTV camera recordings.
The Daesh terror group (banned in Russia) reportedly claimed responsibility for the blast.
The London bombing is the third terrorist attack in the British capital thus far in 2017. In June, a trio of Daesh-associated Islamic extremists conducted a van-ramming attack on London bridge, killing eight before being shot dead by police.