Emergency services were called to Canal Terrace at around 10am on Saturday after the pair, aged 28 and 29, were assaulted by two men in dark clothing.
The younger victim was taken to the Royal Alexandra Hospital in Paisley for treatment while the 29-year-old was taken to the Queen Elizabeth Hospital in Glasgow.
Both are said to be in a stable condition.
Detective Inspector Ian Ross said: “Two men have been viciously attacked in broad daylight and it is absolutely vital that we trace the individuals responsible.
“I would appeal to anyone who was in the area of Canal Terrace around 10am who may have seen or heard a disturbance, or noticed two men acting suspiciously, to please get in touch.
“Anyone with information is asked to contact Paisley CID via 101, quoting incident number 1289 of Saturday 27 January 2018.
“Alternatively you can call Crimestoppers on 0800 555 111 where details can be given in confidence.”