Rossum's 68-yard touchdown and playoff-best 152 punt return yards helped the Falcons cruise past the St. Louis Rams 47-17 in the NFC divisional playoffs Saturday night.
The 5-foot-8 specialist took his first return of the game back for a score in the second quarter, helped by a little trickery.
With Falcons rookie cornerback DeAngelo Hall also lined up deep for the return, Rossum caught the punt and then faked a lateral to Hall.
The Rams took the bait, leaving open field straight ahead for Rossum.
"All I had ahead of me was the punter," Rossum said. "I got tackled by the punter earlier in the season. I didn't want that to happen. I didn't want to be a laughingstock."
No worries. The longest punt return in Atlanta's postseason history gave the Falcons a 28-14 lead.
"I just hit it as hard as I could," he said. "I'm just glad DeAngelo is such a threat."
Rossum added a 39-yard return to the St. Louis 32 to set up a touchdown early in the third quarter and then crossed the field for a 45-yard return to the Rams' 13 to set up a field goal later in the quarter.
The previous NFL record of 143 yards was set by Minnesota's Anthony Carter against New Orleans in 1987.
Rossum added four kickoff returns for 80 yards for a total of 232 return yards and helped expose the Rams' woeful special teams.
The Rams ranked 30th in punt coverage and 32nd in kickoff coverage. In the regular season, Rossum averaged 12.4 yards per punt return, second in the league.
"There is no excuse for anything that we allowed him to do," Rams special teams player Mike Furrey said. "He succeeded and we didn't."
Rossum said he had no idea he had set a record until it was mentioned in the fourth quarter.
"I guess it will settle in later on," he said. "The most important thing is we got the win."
Rossum passed Billy "White Shoes" Johnson as the Falcons' all-time leading punt returner in Week 14 against Carolina. He also passed Deion Sanders' team record for career kickoff return yards.
Rossum, better known for return skills than his work as a cornerback, had the first two interceptions of his career this season and made one start in the secondary.