Former bankers Jay Merchant, 45, Alex Pabon, 38, and Jonathan Mathew, 35, were sentenced to six and a half years, two years and nine months and four years respectively after having been found guilty of conspiracy to defraud.
Fellow former banker Peter Johnson, 61, was sentenced to four years having pleaded guilty in October 2014.
The four will only serve half of their sentences in custody before being released on licence.
The prosecution said that the four former bankers played roles in a scheme to manipulate US dollar linked Libor between June 2005 and September 2007.
After an 11-week trial, Merchant was found guilty by an unanimous verdict, while Mathew was found guilty by a majority verdict of 11-1 and Pabon by 10-2.
A charge of conspiracy to defraud carries a maximum sentence of 10 years.
The trial, which was heard at Southwark Crown Court, was the third brought by the Serious Fraud Office (SFO) in its ongoing investigation into Libor manipulation.
So far, the SFO has secured five convictions as part of the high-profile probe. Former UBS and Citigroup trader Tom Hayes was found guilty last August on eight counts of conspiracy to defraud in relation to manipulating yen-linked Libor.