The advocacy group Glaad analysed shows seen or to be shown between June 2016 and May 2017 and counted 278 regular and recurring LGBT characters.
The number of transgender characters has risen from seven to 16 this year.
But Glaad bemoaned the fact that more than 25 lesbian and bisexual female characters died or were killed off.
They include the characters Poussey Washington and Bea Smith, who met violent ends in Orange is the New Black and Wentworth respectively.
The report also found a record high percentage of black characters on broadcast television, thanks mostly to shows like Empire, Luke Cage and How to Get Away with Murder.
Glaad's Where We Are on TV study based its findings on scripted broadcast, cable and streaming series already being shown or for which casting had been confirmed.
Glaad's president Sarah Kate Ellis said it was "heartening to see progress being made" but said numbers were "only part of the story".
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