The striker came on as a second half substitute at Barnsley to make a landmark appearance aged just 16 years, five months and three weeks.
Williams is the youngest since Tom Murray played in a 3-0 top flight defeat at Sheffield Wednesday in 1905.
Luke Williams: “I enjoyed it, It was great.
“I had no idea I was going to play until the manager told me to warm up - and run!
“He just said to ‘go and do what you’ve been doing and enjoy it’ and I did enjoy it.
“I’m buzzing now. It’s all come so fast,” said Williams, who is qualified for England and the Republic of Ireland.
“This season I was hoping just to play for the Under-18 side but now I just want to play more games for the first team.
“The manager has taken me under his wing and given me my first real chance."