Kristopher Gibson claimed the 16-month term imposed on him for the hate crime attack outside a bar in east Belfast was manifestly excessive.
But the Court of Appeal ruled that the 33-year-old had already received generous credit when he eventually admitted his guilt.
Dismissing the challenge, Lord Justice McCloskey said: “This was a nasty, purely homophobic attack perpetrated without warning against a defenceless and unprepared female.
“The attack was both cowardly and sudden, very substantial force was obviously used.”
Gibson, of Bloomfield Parade in Belfast, launched his assault on the victim in the early hours of May 17 last year.
She was standing with her wife and friends outside a bar on the Upper Newtownards Road when he approached aggressively and started “mouthing about gays”, the court heard.
He then punched the woman in the face, knocking her unconscious, and repeatedly shoved a man who went to her aid.
Goading others at the scene, Gibson proclaimed: “What a right hook I’ve got.”
Witnesses said he was drunk and agitated, shouting ‘f***ing gays’ and other homophobic slurs.
He fled when police arrived, but was pursued and detained nearby, struggling with officers during the arrest.
The victim was taken to hospital for treatment to a head laceration and facial injuries.
She is still suffering psychologically and physically, and may require cosmetic intervention.
Gibson, a-father-of-two, initially denied that he carried out what was described as a “brutal” attack.
But at Belfast Crown Court earlier this year he admitted inflicting grievous bodily harm on the woman, assaulting the man who came to her aid, and an assault on police.
He was ordered to serve eight months in prison, followed by a further eight months on licence.
Defence lawyers argued that the trial judge had got it wrong, based on the lower sentencing range available if the case had instead been dealt with in the Magistrates’ Court.
Barrister Richard McConkey also stressed the impact on his client’s family from sending him to jail during the pandemic.
Appeal judges held, however, that Gibson’s personal circumstances were outweighed by the need to deter any similar homophobic attacks.
“The victim was knocked to the ground (and) she was unconscious for some time,” Lord Justice McCloskey pointed out.
“The sentence imposed fell comfortably within the band reasonably available to the sentencing judge.”