Police were called to Wandsworth Bridge Road just after 7.30.
The 36-year-old driver and his 30-year-old female passenger were arrested on suspicion of causing serious injury by dangerous driving.
They remain in police custody and the man’s family are being supported by specialist officers.
Detective Sergeant Davina Nash said:
“This is a serious collision where the victim suffered life-threatening injuries. My thoughts remain with him and his loved ones.
“I would like to appeal to anyone who was in the area and witnessed the incident, or who has dashcam footage that could help our enquiries, to get in touch with us.”
Anyone with information or dashcam footage is asked to contact police on 101, quoting CAD 6694/16FEB, or Crimestoppers, anonymously, on 0800 555 111.
