The first song to top the Billboard Hot 100 chart when it debuted in 1958 was "Poor Little Fool" by Ricky Nelson, reaching number one on August 4, 1958

. Note that this refers to the first number-one song on the Hot 100 chart itself, which was launched in 1958. If you mean the first song to debut at number one (enter the chart directly at the top spot), that milestone was achieved much later by Michael Jackson's "You Are Not Alone" on September 2, 1995