Unbelievable Power: The Rookie Who Shattered MLB Home Run Records and Left Fans Stunned

Hitting your first big-league homer isn’t just a milestone—it’s a surge of pure adrenaline that every rookie dreams about. But here’s the kicker: some rookies don’t just stop at one or two—they absolutely obliterate records, with power numbers that rival the finest veterans. Remember Aaron Judge in 2017? That guy shattered a 30-year-old rookie home run record, only to have Pete Alonso quietly edge him out a couple years later with a stunning 53 homers. Makes you wonder—what’s going through these young slugger’s minds as they turn rookie jitters into crowd-thunderous bombs? Dive into this jaw-dropping list of rookies who didn’t just dip their toes, but cannonballed into MLB history, smashing homers in single games, entire seasons, and even postseason battles. Ready to ride this home run rollercoaster? LEARN MORE.

Hitting a homer for the first time in the big leagues is undoubtedly an adrenaline rush.

Some players will knock out a dozen or so during their rookie season. And others showcase their power, crushing as many as a seasoned veteran would in a career year.

In 2017, Aaron Judge broke the rookie home run record that had stood for 30 years – and just a couple of years later, Pete Alonso snuck past him with one more.

Below is a list of the most home runs by a rookie in Major League Baseball history in a single game, regular season and postseason.

Most Homers in a Season by a Rookie

1. 53 – Pete Alonso, New York Mets (2019)

Alonso kept fans on the edge of their seats as he vied for the rookie home run record, surpassing the newest mark set just two years before. The true rookie knocked out five homers in his first 10 games and hit 25 more before the All-Star break – where he proceeded to win the Home Run Derby. And Alonso clobbered 11 long balls in September, hitting his record-tying and record-breaking homers in the last three games of the season.

2. 52 – Aaron Judge, New York Yankees (2017)

With his 52 homers in 2017, Judge became the first player in MLB history with at least 50 in their rookie season. And like Alonso, Judge crushed 30 homers prior to the All-Star break and would go on to win the Home Run Derby. The Rookie of the Year slowed down his production over the second half of the season but caught fire with 15 round-trippers in September. While he recorded the most strikeouts by a rookie (208), Judge simultaneously set the highest walk mark (208) and finished the season hitting a homer every 10 at-bats.

Most Home Runs By a Rookie in MLB History

3. 49 – Mark McGwire, Oakland Athletics (1987)

For three decades, McGwire held the major league record for rookie homers (until Judge broke it in 2017). Big Mac hit 15 homers in May and at one point, the first baseman hit three in a game and followed it up with two the following day. And unlike both Alonso and Judge, McGwire had more hits (161) than Ks (131), ultimately batting .289 on the season. The slugger – who did not win MVP even in a 70-homer season in 1998 – would go on to hit at least 30 dingers 11 times in his career.

Most Homers in a Single Game by a Rookie

1. 4 – Nick Kurtz, Athletics (2025)

The A’s phenom put together an epic power display with his four homers against the Houston Astros on July 25, 2025, but he also had one of the best all-around performances of all time. The 22-year-old first baseman went 6 for 6 with eight RBIs in the 15-3 win.

We’ll overlook the fact that his record-breaking homer came in the ninth inning off outfielder Cooper Hummel.

Most Homers in a Postseason by a Rookie

1. 10 – Randy Arozarena, Tampa Bay Rays (2020)

Arozarena surpassed his season total of seven homers with a rookie single-season record of 10 in the playoffs. He knocked out a solo shot against Gerrit Cole in the American League Division Series against the Yankees before homering in the next two games. After the Rays won the series in five games, Arozarena hit four round-trippers against the Astros. The last of which came in a 4-2 win in Game 7, propelling the Rays to the World Series. The hitter went yard three more times in the Fall Classic, including a solo shot in Game 6 that proved futile as the Dodgers won the title that same game.

2. 6 – Evan Longoria, Tampa Bay Rays (2008)

Longoria started off the 2008 ALDS with a bang, knocking out two home runs in Game 1 against the White Sox. The Rays sent them home in four games, and in the AL Championship Series against the Red Sox, Longoria hit a homer in four consecutive games. The slugger had three RBIs in a 9-8 win in Game 1 and helped the team take a 3-1 lead in the series. After narrowly eliminating Boston in seven games, the Rays made their first World Series appearance in franchise history. With just one hit and no homers, Longo had run out of steam and the Rays lost in five games.

3. 5 – Kyle Schwarber, Chicago Cubs (2015)

In his 2015 rookie season, Schwarber nearly single-handedly won the Wild Card Game against the Pirates. The outfielder hit a homer and drove in three of the team’s four runs, sending the Cubs to the National League Division Series against the Cardinals. Schwarber provided run support for the team with homers in three consecutive games as Chicago advanced to the NL Championship Series for the first time since 2003. Though Schwarber hit two dingers, the Mets extended the Cubs’ title drought with a sweep.