Ansah grew up playing soccer and had never seen American football as a youth. In addition to soccer, Ansah was also an enthusiastic basketball fan. He regularly played pickup basketball games at Golden Sunbeam Montessori School where he attended from 4th grade to 9th grade. He developed his basketball interests and abilities on a turf donated by Forever Young Foundation (Steve Young). Ansah played on the Golden Sunbeam basketball team and became the most valuable player and led his team to win many games. Because of the school's basketball facility, attention was drawn from basketball enthusiasts including missionaries of The Church of Jesus Christ of Latter-day Saints (LDS Church). It was at these pickup basketball games with missionaries and students that Ansah developed a friendship with Ken Frei, an LDS Church missionary. Ansah was later baptized a member of the church at age 18. Frei, who taught and baptized Ansah, kept in touch with Ansah after returning to the United States. Frei later suggested that if he was serious about basketball, Ansah should come to Brigham Young University and try out for the basketball team.
Ansah joined the Presbyterian Boys' Senior Secondary School, Legon in 2004. He studied business. During his stay in the school, Ansah actively participated in sports, playing an active role in the basketball team while also participating in track and field sports. During his stay in high school, he was a resident of Kwansa House. He graduated from High School in Ghana in June 2007 and returned to Golden Sunbeam as a Teaching Assistant where, in his spare time, he trained the pupils in basketball.
Under his mentoring, the Golden Sunbeam basketball team won several tournaments while playing international schools in Ghana. When the West African Senior Secondary Certificate Examination (WASSCE) results became public, Ezekiel had 7A's and a B in his Business program.
Ansah applied to and was accepted at Brigham Young University with the help and support of Golden Sunbeam and the assistance of his friend, former ICT teacher and mentor, Alma Ohene Opare who was at BYU at the time. Ezekiel's academic records enabled him to receive an academic scholarship in 2008. Alma Ohene Opare and later Ken Frei played critical roles in helping Ezekiel Ansah adjust to his new surroundings and culture in a new country. Ansah tried out for the BYU Cougars men's basketball team twice, but was cut from both the 2008 and 2009 teams. After facing rejection in basketball, Ansah successfully walked on to the BYU Cougars track team, where he ran a 10.91 in the 100 meters in addition to clocking a time of 21.89 seconds in the 200 meters.
Finally, Ansah was persuaded to try out for the BYU Cougars football team, successfully walked onto the team, and played for the Cougars from 2010 to 2012.
Unfamiliar with American football, Ansah had to be instructed in the most basic rules and techniques, even needing help getting on his pads for the first time. Midway through the 2010 season Ansah made his first collegiate appearance in the Cougars' game versus Wyoming where he recorded his first tackle. During the 2010 season he saw action in six games on special teams and the defensive line, recording three tackles and a pass breakup.
The 2011 season was Ansah's fourth year in school but only third year of eligibility. He played sporadically on third downs as a defensive end or outside linebacker, recording seven total tackles for the season.
For the 2012 season Ansah resumed his role as a situation player. However, during week four, noseguard Eathyn Manumaleuna hurt his knee and Ansah took his place. Over the final nine games of the season Ansah was third on the team in tackles (48), second in sacks (4.5) and first in tackles for loss (13).
For the 2012 season, the BYU Cougars led the nation in red zone defense (opponent red zone percentage of .62), was second in rushing defense (84.25 yards/game), third in 3rd down conversion percentage (27.71%) and total defense (allowing 26.33 yards/game), fourth in First Downs defense (14.83/game), and fifth in scoring defense (176 total points). Additionally, they were in the top 25 in passing defense (13th), quarterback sacks (22nd), fourth down conversion defense (23rd), and tackles for loss (25th).
All statistics from Brigham Young Official Athletic Site,
Ansah was not found on any of the 2012 preseason mock drafts for the 2013 NFL draft. By mid-season, he had moved up from unlisted to the late-first round or early second round with many analysts calling him the sleeper pick of the draft. Ansah further improved his draft stock with his "outstanding defensive player" outing in the 2013 Senior bowl, where he recorded seven tackles (six solo), 1.5 sacks (for 13 yards), 3.5 tackles for loss (for 24 yards), a pass breakup, and a forced fumble.
In March 2013, reports began to circulate questioning the accuracy of Ansah's age. His passport, however, shows his date of birth as May 29, 1989.
Coming out of college, he was projected by analysts and scours to be a first round draft selection and was a consensus top 10 pick. He was ranked the top defensive end and the seventh best player by NFLDraftScout.com. Although he was thought of as a raw talent who was a boom or bust prospect that lacked stamina, his large frame, size, quickness, athletic ability, consistency, and unparalleled length and foot speed made him too valuable to pass on.
Ansah was drafted by the Detroit Lions, in the first round, with the fifth overall pick, of the 2013 NFL Draft. On May 10, 2013, the Detroit Lions signed him to a fully guaranteed four-year, $18.59 million contract with a signing bonus of $11.90 million.
He entered training camp competing to be the right starting defensive end. In the first week of the preseason, Ansah intercepted Mark Sanchez and returned the ball 14 yards for the first score of the game. Head coach Jim Schwartz named him the backup right defensive end behind Willie Young to begin the regular season after his development was delayed due to a head injury he suffered in practice.
He made his professional regular season debut in the Detroit Lion's season opener against the Minnesota Vikings and made three combined tackles and was credited with half a sack on Christian Ponder in a 34-24 victory. On September 22, 2013, Ansah earned his first career start after Jason Jones was placed on injured reserve for the remainder of the season with a knee injury. He made a season-high seven combined tackles and sacked Robert Griffin III twice, one causing a fumble, in a 27-20 victory over the Washington Redskins. He returned in Week 12 after missing the last two games with an ankle injury. In Week 12, he recorded two solo tackles and sacked Mike Glennon twice, as the Lions lost to the Tampa Bay Buccaneers 24-20. The following week, he made three solo tackles and two sacks on Matt Flynn in a 40-10 victory over the Green Bay Packers.
Ansah finished his rookie season with 32 combined tackles, 8 sacks, 2 forced fumbles, and a pass deflection in 14 games and 12 starts. His eight sacks led all NFL rookies and ranked second in Lions rookie history. He was named the Mel Farr Rookie of the Year, honouring the Detroit Lions' most outstanding rookie.
He returned as the right defensive end in 2014 and was named the starting defensive end, by new head coach Jim Caldwell, to begin the regular season. In the season opener against the New York Giants, he recorded an assisted tackle and was credited with half a sack on Eli Manning in a 35-14 victory. On October 12, 2014, Ansah made five combined tackles and was credited with a season-high 2½ sacks on Teddy Bridgewater, as the Detroit Lions defeated the Minnesota Vikings 17-3. In Week 10, he racked up a season-high six solo tackles and had one sack on Ryan Tannehill in a 20-16 win over the Miami Dolphins. Ansah finished his second season with 49 combined tackles, 7½ sacks, and three forced fumbles in 16 games and 16 starts.
On January 4, 2015, Ansah started his first career playoff game and made two solo tackles and a sack on Tony Romo in a 24-20 loss to the Dallas Cowboys.
He started the Detroit Lion's season-opener against the San Diego Chargers and made two solo tackles and a sack on Philip Rivers in a 33-28 loss. The next game, Ansah recorded a season-high seven solo tackles (six solo) and a sack in a 26-16 loss to the Minnesota Vikings. On November 26, 2015, he racked up four combined tackles and was credited with a season-high 3 sacks on Mark Sanchez, as the Detroit Lions routed the Philadelphia Eagles 45-14.
In the 2015 season, Ansah made 47 combined tackles, 14½ sacks, 4 forced fumbles, and a pass deflection in 16 games and 16 starts. He finished third in the league with 14½ sacks (J. J. Watt 17½, Khalil Mack 15) and tied William Gay (13½ sacks in 1983) for the second-most sacks in a season by a Lions defensive player since 1982, trailing only Robert Porcher (15.0) set in 1999. Ansah was named to the Pro Bowl for the first time in his career. On January 31, 2016, during the Pro Bowl, Ansah was a part of Team Irvin and made one solo tackle in a 49-27 win over Team Rice He was ranked 43rd on the NFL Top 100 Players of 2016.
On May 2, 2016, it was announced that the Detroit Lions exercised the fifth-year option on Ansah's contract rookie contract that will pay him $7.53 million for 2017.
He started the Detroit Lion's season opener against the Indianapolis Colts and made two combined tackles in a 39–35 victory. The following week against the Tennessee Titans, Ansah injured his ankle on the second play of the game, and missed the next three games. In a Week 9 victory over the Minnesota Vikings, Ansah racked up a season-high five solo tackles. On December 18, 2016, he recorded five combined tackles and sacked Eli Manning for his first of the season. He finished his season with 35 combined tackles and two sacks in 13 starts. The two sacks was a steep decline from the 14.5 he posted the previous year.
The Detroit Lions finished the year 9–7, and clinched a wild card spot. During the wild card round against the Seattle Seahawks, Ansah made five combined tackles and sacked Russell Wilson twice, but the Lions lost 6–26.
KeyGP: games played
COMB: combined tackles
TOTAL: total tackles
AST: assisted tackles
FF: forced fumbles
FR: fumble recoveries
FR YDS: fumble return yards
IR YDS: interception return yards
AVG IR: average interception return
LNG: longest interception return
TD: interceptions returned for touchdown
PD: passes defensed
Ziggy is the youngest of five children. His father, Edward, was a sales manager for a petroleum company, and his mother, Elizabeth, was a nurse. Ansah is an active member of The Church of Jesus Christ of Latter-day Saints (LDS Church). Ansah was assigned to room with Kyle Van Noy, a highly touted linebacker, during the 2012 season. The two have maintained a close relationship both on- and off-the-field. Ansah reported in a Sports Illustrated interview that, "Kyle is like a brother to me." While attending BYU Ansah worked for several years as a custodian in order to pay his tuition (he stopped working when he was awarded a scholarship his senior year).