CANBERRA, Australia—The most senior Catholic official to be convicted of concealing child sex abuse has been sentenced by an Australian court to home detention, avoiding a jail term due to his age and frail health.

Philip Wilson, 67, stepped aside from his duties as archbishop of Adelaide in May after being found guilty of concealing the sexual abuse of children in the 1970s by convicted pedophile priest James Fletcher, who died in jail in 2006.

“By...