A native of Newport Beach, California, Arenado attended El Toro High School in Lake Forest before becoming the Rockies' second-round selection in the 2009 MLB draft.

Nolan James Arenado was born in Newport Beach, California, and raised in nearby Lake Forest, an Orange County city sandwiched between Irvine, Mission Viejo and Laguna Hills.

[10] As a senior, Arenado batted .517, .615 on-base percentage (OBP), five home runs (HR), 14 doubles, and a triple,[11] and was again named to the Los Angeles Times' All-Star team.

[13] Rather than attend ASU, he signed with the Rockies, and made his professional baseball debut with the Casper Ghosts of the Rookie-level Pioneer League, where he batted .300.

The work ultimately gave him a combination of explosive vigor, ingenuity, and finesse that allowed him to cover large areas and make good long and short throws from postures ranging from upright to nearly laying down.

[24] In his sixth game, he hit his first major league grand slam and second career home run off Tampa Bay Rays pitcher David Price.

[27] Defensively, he led NL third basemen in range factor both per game (3.08) and per nine innings (3.24), and was second in putouts (91), assists (309) and double plays turned (tied with two others with 27).

[31] On May 23, Arenado suffered a mallet fracture of his left middle finger on a headfirst slide into second base in a game against the Atlanta Braves, and was subsequently placed on the 15-day disabled list (DL).

[35][36] Playing against the San Francisco Giants on September 5, Arenado homered in his sixth consecutive game, breaking the Rockies' team record of five which Dante Bichette and Larry Walker shared.

[37] He won his first NL Player of the Month award in September, batting .339 and leading the major leagues with 11 home runs, 32 RBI, and 79 total bases.

[38] For the 2015 season, Arenado tied Bryce Harper for the NL home run title with 42,[39] and led the National League with 130 RBI and 354 total bases.

In addition, he batted .287 with a .323 OBP, .575 SLG, .898 OPS, 43 doubles, and 11 sacrifice flies (leading the majors) on his way to winning his first Silver Slugger Award for third basemen.

Additionally, Arenado set a major league record for extra base hits by a third baseman in one season with 89, surpassing Chipper Jones' total of 87 in 1999.

[46] He received official consideration for the NL MVP Award for the first time, ranking eighth in voting behind Harper, Paul Goldschmidt, Joey Votto, Anthony Rizzo, Andrew McCutchen, Jake Arrieta, and Zack Greinke.

Before spring training, on January 13, 2017, Arenado and the Rockies avoided arbitration for the second straight year by agreeing to a two-year, $29.5 million contract.

It was just the sixth time[a] in MLB history that a hitter completed the cycle with a walk-off home run; Arenado's teammate Carlos González was the previous to do so, on July 31, 2010.

For the first time in his career, Arenado was selected to start in the MLB All-Star Game, played at Marlins Park in Miami, after receiving the most fan votes of all National League third baseman.

[62]With a two-run home run versus José Ureña of the Miami Marlins on August 11, Arenado became the first major leaguer of 2017 to reach 100 RBI for the third year in a row, doing so in 112 games.

[16] Writing for The Sporting News, Joe Rivera noted, that per Fangraphs, Arenado was the fourth player in history to net at least 100 defensive runs saved within his first five seasons (103).

[69] Arenado finished the season with a .309 batting average, 187 hits, 43 doubles, seven triples, 37 home runs (tied for third most in the league with teammate Charlie Blackmon and Miami's Marcell Ozuna), and 130 RBI.

"[72] An amplitude of defensive accolades eventualized including a fifth straight Gold Glove Award, making him the first infielder to arrogate this in each of his first five seasons in the major leagues.

[79] On April 11, San Diego Padres pitcher Luis Perdomo threw a pitch behind Arenado, who charged the mound and incited a bench-clearing brawl.

[83] After producing a first half batting .305, 22 home runs and 63 RBI, Arenado was voted to start the 2018 MLB All-Star Game for the second year in a row, and fourth selection overall.

[90] Arenado finished the 2019 season hitting .315/.379/.583 in 154 games and making just nine errors, setting new career-highs in batting average, OBP, fielding percentage (.980), fWAR (5.9), bWAR (6.7), and on-base plus slugging (.962).

[94] On February 1, 2021, the St. Louis Cardinals acquired Arenado from the Rockies along with $51 million in exchange for Austin Gomber, Mateo Gil, Tony Locey, Elehuris Montero, and Jake Sommers.

[107] He was named April Player of the Month for the National League after having batted .375 with five home runs, 17 RBIs, 12 extra-base hits and a league-leading 1.125 OPS.

[112] On July 24, it was announced that Arenado, along with teammate Paul Goldschmidt, would not be allowed to travel with the Cardinals to Toronto for a scheduled series against the Blue Jays, due to his lack of a COVID-19 vaccination.

[116] He was named a finalist for the National League Most Valuable Player Award alongside teammate and eventual winner Paul Goldschmidt and Manny Machado.

When Rockies manager Bud Black visited him at the campus of University of California, Irvine, in January 2017, Arenado asked to take ground balls at third base.

[128] Arenado's favorite players are fellow third basemen Adrián Beltré of the Texas Rangers and Rockies teammate and outfielder Matt Holliday.