John Allen, 73, was convicted by a jury at Mold crown court of committing various offences at a number of residential properties in and around the Wrexham area.
He was found guilty of 21 counts of indecent assault, one charge of indecency with a child and four serious sex assaults.
Allen was cleared of two other serious sexual assaults.
The jury is continuing to deliberate on 12 counts.
Opening the case, prosecutor Eleanor Laws QC, said Allen created “a sexualised atmosphere alongside a culture of fear”.
She said Allen employed staff to look after the children but he involved himself in some of the work duties including at night and was “a regular and formidable presence”.
Laws said boys at the homes described Allen as being abusive and at times violent and would often be under the influence of drink.
Most of the victims felt they had no choice but to put up with Allen’s attentions as they became “hardened to the abuse”, she added.
The jury had been told that Allen was convicted in 1996 of indecently assaulting six boys, aged between 12 and 16, at his care homes in the 1970s.
Allen claims that was a miscarriage of justice.
Allen from Ipswich, had denied 29 counts of indecent assault, nine other serious sexual assaults and two counts of indecency with a child, on various dates between the late 1960s and 1990.
The case was adjourned until Thursday when the jury will return to resume its deliberations.