Police responded to a brawl involving baseball bats and sticks at roughly 5.30pm on Tuesday.
The victims, in their 20s, were found by Met, British Transport Police and paramedics with injuries at the scene.
Three men, whose ages are not known, have since been arrested on suspicion of grievous bodily harm and remain at an east London police station.
Transport for London said Poplar DLR station was closed while police carried out an investigation. It has since reopened.
The Metropolitan Police said: “Police were called at 17:36hrs on Tuesday, 26 September to reports that two men had been found with injuries at Poplar DLR Station.
“Officers attended along with colleagues from the British Transport Police and the London Ambulance Service.
“Two men, aged in their 20s, were found with injuries after being assaulted.
“They were taken to hospital where their injuries are being assessed.
“Three men were arrested nearby on suspicion of grievous bodily harm and were taken into custody at an east London police station.
“An investigation is under way and enquiries are ongoing to establish where the men were assaulted.”
Any witnesses are asked to call 101, quoting CAD 6205/26Sep, or Crimestoppers anonymously on 0800 555 111.