"What a legend young cratsy ... qualified for the Olympic final good boy!!! Very proud ... #whatalegend @Brandonstarc93," his brother, Australian cricketer Mitchell Starc, tweeted to his 476,000 followers.
However, outside of family support, it seems GoT devotees are leading the celebrations.
Cathy O'Malley tweeted Starc was "taking time off from Game of Thrones" to compete in the event, while other fans joked about the character's troubled fate.
"Great to see him walking again," tweeted Brit Dan Wilde, referring to the fictional Stark's inability to use his legs after he is pushed out of a tower in season one.
"Brandon Starc may be a pretty good high jumper but Brandon Stark is a better long faller," Twitter user Rob Wycoff, of England, said.
Athletics Australia has also started using the hashtag #HouseStarc in their posts about the high jumper, mimicking the popular use of #HouseStark by fans of the show.
Starc will compete in the 15-man final on Wednesday morning Australian time.