London Buses operates a bus from Westminster to Knightsbridge every 10 minutes. Tickets cost $3 and the journey takes 10 min. Green Line (operated by First in Berkshire) also services this route hourly.
From St. James's Park Underground Station Tube to South Kensington Underground Station. 6 min £2. From Victoria bus to Knightsbridge Barracks. 10 min £2. From Westminster taxi to Knightsbridge. 3 min £9. From Westminster Uber to Knightsbridge. 3 min £7. From Westminster walk to Knightsbridge. 31 min. From Howick Place, Westminster Bikeshare to Montpelier Street, Knightsbridge. 9 min.