The Irish bouzouki (Irish: búsúcaí) is an adaptation of the Greek bouzouki (Greek: μπουζούκι). The newer Greek tetrachordo bouzouki (4 courses of strings) was introduced into Irish traditional music in the mid-1960s by Johnny Moynihan of the folk group Sweeney's Men, who retuned it from its traditional Greek tuning C³F³A³D⁴ to G²D³A³D⁴, a tuning he had pioneered previously on the mandolin. Alec Finn, first in the Cana Band and subsequently in De Dannan, introduced the first Greek trichordo (3 course) bouzouki into Irish music.

In the early 1970s, Andy Irvine, who was a member of Sweeney's Men with Johnny Moynihan, gave a Greek tetrachordo bouzouki to Dónal Lunny, who replaced the octave strings on the two lower G and D courses with unison strings, thus reinforcing their lower frequencies. Soon after, on a visit with Irvine to the workshop of luthier Peter Abnett, Lunny commissioned a four-course bouzouki with a three-piece, partially staved back. This was the first bouzouki built specifically for Irish music. Since then, the instrument has been adapted by many instrument builders for Irish traditional and other styles of folk music.

With a few exceptions, instrumentalists playing the bouzouki in Irish music tend to use it less for virtuoso melodic work, and more for the chordal or contrapuntal accompaniment, the melodies being played on other instruments, such as the flute or fiddle. A few individuals though, have pioneered the bouzouki's application for melodic work, including such players as Pat Kilbride, Brian McNeill, Jamie McMenemy, Gerald Trimble, Roger Landes, Ross McNerney and others.^{[citation needed]}

The original Greek bouzouki is a three course / six-string instrument (trichordo) tuned D₃−A₃−D₄ (with an octave pair on the lower course). In the 1950s, a four course / eight-string (tetrachordo) version was developed in Greece, tuned C₃−F₃−A₃−D₄ (with octave pairs on the C and F courses) and popularized by Manolis Hiotis. The modern tetrachordo bouzouki was noticed by Irish musicians, who adopted and adapted it for accompaniment in Irish folk music, from whence it has diffused into other folk genres.

Johnny Moynihan is credited with bringing the first tetrachordo Greek bouzouki to Ireland and retuning it to G₂−D₃−A₃−D₄ (intervals he had first used on the mandolin). However, according to Leagues O'Toole, Moynihan bought his first bouzouki from his friend Tony Ffrench, who had brought it back to Ireland from Greece, but decided he couldn't play it, or didn't want to.

In the mid-1960s, Moynihan established a presence for the instrument in Irish music with the popular folk trio Sweeney's Men. During the recording of their 1968 eponymous album, Sweeney's Men, Andy Irvine also played Moynihan's bouzouki on the track "Johnston".

Shortly after he returned from Eastern Europe in late 1969, Irvine met Dónal Lunny – who had been playing guitar up to that point – and gave him a Greek bouzouki he had brought back from his travels. Being left-handed, Lunny reversed the strings and, crucially, replaced the octave strings on the two lowest courses with unison strings, thus fundamentally changing the character of the instrument.

Approximately a year later, Lunny accompanied Irvine to Peter Abnett's workshop and commissioned a partially staved-back instrument with similar specifications, marking the first Irish bouzouki to be specially made. This modified bouzouki was first integrated into Irish folk music when Irvine and Lunny popularized it with the advent of Planxty in 1972.