Raised in Carthage, Texas and later Dallas, Ja'Marcus attended South Oak Cliff High School — one of nine siblings — where he played receiver and couldn't crack the varsity lineup until his senior year. At 5'10" and 140 pounds as a junior, he was still growing into his body. When he finally got his shot, he delivered: 26 catches, 750 yards, 6 touchdowns, and Texas Class 5A Region II District 11 first-team honors. No college offers came anyway. He walked on at Utah State — and showed up standing 6'1", 195 pounds, with something to prove.

He arrived at Utah State without a scholarship or a promise — and earned his way into the starting lineup. As a true freshman in 2017, Ja'Marcus played all 13 games with 10 starts and led the Aggies' cornerbacks with 42 tackles, adding five pass breakups and a 25-yard interception return at Air Force. Scouts described him as "long and athletic... physical and a great cover guy." His sophomore season was cut short by injury after six games, but the two-year body of work told the story: 19 starts, 61 tackles, 11 pass breakups. The walk-on had become a cornerstone.

He followed head coach Matt Wells from Utah State to Texas Tech, arriving mid-camp and playing in all 12 games of his junior season — splitting time between cornerback and safety. He played the back half of 2019 with a cast on his hand, including an interception in the end zone against Baylor that killed a drive inside the 5-yard line with the Bears leading. As a senior he led the team in special teams tackles. He enrolled in graduate school, earned his degree, and then entered the transfer portal — one year of eligibility left, one more proving ground ahead.

He used his final year of eligibility at Buffalo — and made every snap count. Starting all 11 games at cornerback, Ja'Marcus posted 47 tackles, 2.5 tackles for loss, a forced fumble, and three pass breakups. The kid who couldn't crack a high school varsity lineup at 5'10" and 140 pounds was now a 6'2" starting cornerback with a graduate degree and a declaration for the NFL Draft. No one called his name on draft night. He signed with the Bills anyway.

Signed as an undrafted free agent in May 2022, Ja'Marcus spent two seasons grinding on the practice squad before cracking the 53-man roster in 2024. Once in, he delivered. In Week 1 against the Arizona Cardinals he broke up a late pass to seal the win. The following week against Miami, he intercepted Tua Tagovailoa twice in the same game — returning the first 31 yards for a touchdown — as the Bills rolled 31-10. He finished 2024 playing all 17 games with 4 pass deflections and a sack. The grind was real. So was the payoff.

Claimed off waivers by the Houston Texans in December 2025 and re-signed in March 2026, Ja'Marcus has found his home. Wearing #20 in a city that matches his energy, he's deepening his roots in the community and proving every week that the underdog story isn't over — it's just getting started.