"Thinking about my family today. Exactly one year ago my little cousin was killed by a drunk driver," the star captioned her Instagram story on Sunday.
"A senseless and reckless act took away a beautiful soul. You'll forever be in our hearts and in the sunsets. Love you, Trevor."
According to the family's GoFundMe page at the time, Trevor and his father, Bryan Canaday, were "driving to a show choir event" together before they were hit by the drunk driver, reported E! News.
The driver accused of causing the accident was charged with manslaughter before the year ended.
Despite the tragic news, Hyland revealed that she would take a break from social media after receiving hate online.
"I'd like to ask those who have negative thoughts or opinions about the tragedy that happened to my family, to keep them to themselves," she expressed. "You don't know all the details. And how dare you attack when a beautiful life has been lost."