More officers will be given handheld metal detectors to protect them following the death of a sergeant who was shot at a custody centre.
Sgt Matiu Ratana, known as Matt, was shot in the chest as he prepared to search a handcuffed suspect at Croydon Custody Centre on 25 September.
Metropolitan Police Commissioner Dame Cressida Dick said the force had made changes to make "everybody safer".
She said custody detention officers were now required to wear body armour.
She said the force would issue more officers with "search wands" to find weapons before suspects are taken into custody.
Louis De Zoysa, 23, was arrested on 13 November on suspicion of the murder of Mr Ratana, 54.
Dame Cressida said officers dealing with the most violent offenders had already been using the wands. The tactic is now being rolled out across the Met.
Speaking on an LBC radio phone-in on Friday, she said "This is just an extra protection, never ever to substitute for a search but may just find a weapon or a knife."
Mr De Zoysa remains in hospital with "life-changing injuries" and detectives will consult with doctors and legal advisers before they begin interviewing him.
He also suffered a gunshot wound and was taken to hospital in a critical condition, but the Met said he had since "stabilised" and was considered fit to be arrested.