Kenny-Dowall became emotional when Magistrate Greg Grogin said all charges against the 28-year-old were dismissed at the Downing Centre Local Court on Monday morning.
Kenny-Dowall was accused of headbutting, pushing and putting former girlfriend Jessica Peris in a headlock.
But Magistrate Grogin said her evidence was "evasive" and "framed to avoid a direct response".
"The complainant was not an impressive witness," he said repeatedly during his hour-long judgment.
The Sydney Roosters player strongly denied allegations relating to the charges.
Kenny-Dowall's barrister Ian Temby QC on Friday urged Magistrate Grogin to dismiss the charges, claiming the prosecution failed to prove their case in the three-day hearing.
Police prosecutor Amin Assaad argued the 28-year-old was a jealous and controlling boyfriend who had anger problems.
Ms Peris was supported in court last week by her mother, Senator Nova Peris, who watched on as intimate details of her daughter's 14-month live-in relationship with Kenny-Dowall were laid bare.
According to Ms Peris the pair argued regularly, as was made clear from a selection of the 40,000 texts the couple exchanged, which were read in court.
The court was also told details of the young couple's "vigorous" sex life.
Magistrate Grogin also found it "extremely unusual" Ms Peris went to the Roosters seeking material support before reporting the alleged domestic violence to police.
Neither Ms Peris nor her mother, Senator Peris, were in court for the result on Monday.
Last week Kenny-Dowall said the various domestic allegations were "not true", "incorrect" and never occurred, but admitted possibly leaving a bruise on Ms Peris after she "attacked him" during a heated argument in 2014.
The court heard last week that Ms Peris tried to get financial support from the Roosters NRL club before going to police with the violence allegations and Kenny-Dowall.
It was told the club offered shelter and a car for a month, but Ms Peris wanted accommodation and a car for six months, and one month's income.
Kenny-Dowall and Ms Peris first met at a Bali bar in 2012 and she moved to Sydney from Darwin in May 2014 to pursue the relationship, which ended little more than 12 months later.
The couple exchanged about 40,000 texts, some endearing and some detailing sexual matters in "graphic terms".
Also mentioned in the texts was a reference to Ms Peris having taken cocaine, the court heard.
One of the charges against Kenny-Dowall related to a claim in October 2014 he sarcastically told his mother "I bashed her" when she asked about a bruise on Ms Peris' arm.
In February 2015, Ms Peris alleged Kenny-Dowall pushed her in the hallway of their home following a dispute over their pet dog Marco.
Ms Peris also claimed Kenny-Dowall kicked at her several times in March 2015 as she tried to enter their bed following an argument.
