Jamar Kasheef Loza was born in Arnett Gardens in Kingston, Jamaica on 10 May 1994, and moved to the United Kingdom as a child. He began his career at Norwich City after coming through the youth team to win a professional contract. On 25 October 2013, he joined League One side Coventry City on a 28-day youth loan; "Sky Blues" manager Steven Pressley said that "Jamar is very quick but he's also very direct and very strong and he's the kind of player that would fit well into our system". He made his debut in the Football League on 2 November, in a 3–0 win over Notts County at Sixfields Stadium, coming on as an 81st-minute substitute for Callum Wilson. The Coventry Telegraph reported that Pressley planned to speak to Norwich manager Chris Hughton about extending the loan deal, though Loza ended up returning to his parent club at the end of the original 28 days. On 6 January 2014, he returned to League One on a 28-day loan at Leyton Orient. He made his debut for the "O's" the following day, and provided an assist for Moses Odubajo to score Orient's first goal in a 2–0 victory win over Shrewsbury Town at the New Meadow. Manager Russell Slade opted to extend the loan into a second month. On 21 March 2014, Loza joined League Two side Southend United on a one-month loan. He made his debut against Oxford United on 24 March, in which he set up the first goal, won a penalty for the second, and then scored what manager Phil Brown described as a "great goal" to complete a 3–0 victory. He made his first team debut for Norwich as a 58th-minute substitute for Alexander Tettey in a 2–0 defeat to Arsenal at Carrow Road on 11 May; the defeat confirmed Norwich's relegation from the Premier League. In total he played 12 games in the 2013–14 season, appearing seven times for Southend, three times for Leyton Orient, and once each for Coventry and Norwich. He signed a two-year extension to his contract, with the option of a further year, in June 2014. On 14 January 2015, Loza joined League One side Yeovil Town on a one-month loan. He featured in five games for Gary Johnson's "Glovers". He came off the bench for Norwich in the Championship on 17 March against Huddersfield Town at the Galpharm Stadium, and scored his first goal for the club eight minutes into injury time to secure a 2–2 draw. He played ten games in the 2014–15 season, five each for Norwich and Yeovil. Loza joined Teddy Sheringham's League Two Stevenage on a one-month emergency loan on 1 October 2015. He returned to Norwich after two games for the "Boro", and scored five goals for the under-21s against Southampton under-21s, but manager Alex Neil admitted that the club's promotion to the Premier League reduced the chances for young players to earn first team opportunities. He returned to Southend United, now in League One, on loan for the rest of the 2015–16 season on 29 January 2016. He was released by Norwich upon the expiry of his contract in June 2016.
Non-League
Loza had a trial at League One club Port Vale in July 2016, but did not sign for the club. On 20 October 2016 Maidstone United announced they had signed Loza, and on the evening of 25 October 2016 he scored his first goal for the club in a 2–2 draw against Sutton United, in the National League. On 5 October 2018, Loza joined National League South side Woking on a three-month loan. On 19 June 2019, after a spell with rivals Billericay Town, Loza signed for Chelmsford City. On 20 September 2019, Loza returned to Woking on loan until January 2020. Once this spell ended, it was then extended until the end of the season. On 13 May 2020, Chelmsford announced the departure of Loza. On 2 July 2020, Loza signed for King's Lynn Town
Speaking in June 2014, Norwich City manager Neil Adams described Loza as "a direct player who is lightning quick and can run with the ball, and he causes defenders a lot of problems". In an interview in January 2015, Loza stated that "I like to run in behind. I love scoring goals, but also I let the ball come to feet as well and link up with play".
