The 49-year-old complied fully with the investigation which included submitting his bank statements, betting account details and electronic devices – a Welsh Rugby Union laptop and mobile phone – used to place the bets.
The report states: "Not surprisingly, Mr Howley was asked a number of questions relating to bets he had placed upon the Welsh team and about a bet which he had placed upon an individual within the team to be the first try scorer in the match against Ireland in March 2019.
"Mr Howley did not deny placing such a bet; indeed he accepted that he had placed the bet. He was at pains to point out, however, that he had placed the bet as part of a "treble" bet and that the bet was part and parcel of his normal recreational betting activity.
"That said, Mr. Howley conceded that he knew that it was in breach of the regulations for him to bet on matches involving Wales and, indeed, that it was also a breach for him to bet on other rugby matches.
"We are also satisfied that Mr Howley made no gains, overall, from these bets. In fact WRU assess that overall Mr Howley made losses of approximately £4,000 ($NZ8091). It is also clear that Mr Howley's betting on rugby was part of a "hobby" of betting on sporting events.
"We use the word "hobby" with some caution because it seems that a trigger for Mr Howley's betting activity was a family tragedy involving the death of his sister.
"Nonetheless, Mr Howley's behaviour was presented to us as being part of his recreational activities and, so far as we can discern, there is no reason to doubt that is so."
Howley was sent home from the World Cup after the WRU became aware of a potential breach of regulations, prompting the launch of an investigation into the allegations and Stephen Jones stepping into his role as attack coach.
Howley's case was heard in Cardiff by an independent panel, chaired by Sir Wyn Williams. The panel has submitted and shared its decision with World Rugby.
The ban is backdated to the time of his withdrawal from the World Cup, and nine months has been suspended, leaving Howley free to return to union on June 16 next year.
Sir Ian McGeechan, Gatland and Lions centre Jonathan Davies provided testimonials.
After serving on Warren Gatland's coaching staff for the past 11 years, Howley had been linked with a move to the Italian national job post World Cup but this scandal has since ruined his hopes of assuming that role.
He was also Wales interim head coach during 2012-13 and 2016-17 seasons while Gatland guided the Lions.
Howley has until Christmas day to mount an appeal against the punishment. He is now seeing a psychologist in a bid to stop gambling.
