Keane is one of nine children.[3] Both of his parents ran the Ringside Rest Hotel in Cahersiveen.[3] His father Tom was a builder who spent time as chairman of the South Kerry board.[3] Peter Keane played football in the late 1980s and early 1990s.[3] He played for St Mary's alongside fellow forward Maurice Fitzgerald.[3] In 1988, the pair won a Kerry under-21 title for South Kerry. However, his county career was limited to minor (1989), county junior (1990) and under-21 (captaining the 1992 team to a Munster title).[3]
He spent four years working in a bank before departing to work in retail in Killorglin.[3] He is considered shrewd.[3] In 2009, he managed Beaufort's junior footballers past his own St Mary's club in the county semi-final and led them to victory over Dromid in the final.[3] He began managing his native club St Mary's in 2010, travelling down from Killorglin especially to do so, and led them to victory in the South Kerry final.[3] Keane's younger brother Ray was playing for the team, this before his own foray into management with St Finbarr's.[3] After leading St Mary's to the 2011 All-Ireland Junior Club Football Championship, Keane joined Kerry's youth development system and managed the Kerry under-16s.[3] County minor manager Mickey O'Sullivan brought him in as a selector in 2011, telling The Kerryman newspaper: "Nobody knows more than Peter does".[3] This was accidental, only coming about because Seán O'Sullivan left a vacancy by coming out of retirement to play for Kerry.[3]
After losing to Cork in the 2020 Munster Senior Football Championship semi-final, Keane climbed Carrauntoohil; there he fell and was rescued by helicopter, requiring surgery on his shoulder after being airlifted to hospital. Keane spoke about the incident ahead of his county's 2021 National Football League opening game against Galway, saying: "I had a very innocuous fall, it was just a slip, and I put my hand back to save myself and unfortunately I dislocated my shoulder".[4]
In November 2024, Keane was ratified as the new manager of the Clare senior football team.