The man remains in custody at a south west London police station.
Police were called at approximately 11.45pm on Monday, 5 July, to a teenager stabbed in Oval Place, SW8.
Officers attended along with London Ambulance Service. Keane, aged 16, was pronounced dead at the scene.
His family are being supported by specially trained officers.
A 29-year-old man was arrested on suspicion of murder on Thursday, 8 July. He was later released on bail to a date in August.
Detectives from the Met’s Specialist Crime Command are leading the investigation and continue to appeal for witnesses.
Anyone with information is asked to call police on 101 or tweet @MetCC quoting CAD 8532/05Jul. To remain 100% anonymous, call Crimestoppers on 0800 555 111.
Hard calls save lives. Are you close to someone on the fringes of knife crime? Do the right thing, please give information, 100 per cent anonymously, through the independent charity Crimestoppers.
No piece of information about knife crime is insignificant or too small. Any information you give to Crimestoppers can make a difference in reducing knife crime and the harm it causes to families.
Crimestoppers never ask your name and they cannot trace your call, your IP address or the device you use. Fill in their quick online form or call 0800 555 111. It could save a life.