Jamar Loza was first noticed when he scored 4 goals for Norwich City Under-16s in a 6-1 thrashing of Ipswich on 21st November 2009. He later played for the Under-18s against Southampton in January 2010. In July 2010, he became a full-time scholar with the Canaries' academy.

Loza shone with the under-18s during 2011/12, netting over 20 goals and featuring heavily for the reserves. He was released in the summer of 2012 but then was recruited for the Under-21 development squad. He made 30 appearances, scoring 13 goals. He travelled with the first team to Austria in the summer of 2013.

On 25th October 2013, Loza joined Coventry on a 28 day youth loan. He made his league debut in the league One clash with Notts County on 2nd November.

On 6th January 2014, Loza was loaned to Leyton Orient on a 28 day loan deal and made his debut, starting up front, the following day in a 2-0 win over Shrewsbury.

On 31st January 2014, Loza's loan was extended until 8th March 2014. He returned to Norwich having made three appearances for Orient.

On 21st March 2014, Loza was loaned to Southend for a month. He made his debut the same day against Bristol Rovers. He made his first start on 25th March 2014 and was named man of the match for scoring once and setting up two others.

Loza made his Norwich City debut on the final game of the 2013/14 season at home to Arsenal, coming on as a substitute.

On 2nd June 2014, Loza was called up by Jamaica for their international friendlies with Egypt and France. He made his debut against Egypt on 4th June as a 84th minute substitute. He went on to win more caps during 2014/15 taking his total to 4.

Loza was linked with a loan move to Swindon at the end of September 2014, despite being a regular on the bench for the Canaries during the opening games of the 2014/15 season. On 14th January 2015, Loza was loaned to Yeovil for a month. He had made five appearances for Norwich during the 2014/15 season ahead of the loan.

Loza scored his first goal for Norwich in injury time at Huddersfield on 18th March 2015, salvaging a point for Norwich in a 2-2 draw. He had come on as substitute. He finished the season with four appearances for City.

On 2nd October 2015, he was loaned to Stevenage for a month. He made his debut the following day in a 1-0 home defeat to Carlisle, and was substituted with Charlie Whelpdale replacing him. He made just two appearances for Stevenage before returning to Carrow Road.

On 29th January 2016, Loza was loaned to Southend until the end of the 2015/16 season

On 10th June 2016, Norwich announced that they would not be renewing his contract. He was quickly linked with returns to former clubs Southend and Yeovil.

He almost signed for Port Vale in July 2016. He then joined Scottish side Inverness Caledonian Thistle on trial in August 2016 playing and scoting for their development squad in a 3-1 win over Motherwell on 23rd August 2016. He then joined Colchester on trial, playing for their Under-23s against Charlton on 29th August 2016.

On 21st October 2016, Loza joined Conference side Maidstone United. He scored his first goal for Maidstone in the 2-2 draw away at Sutton on 25th October 2016.

In October 2018, he joined Woking on a three month loan. On 11th January 2019, he was sold to Billericay Town for an undisclosed fee. He moved to Chelmsford City in late June 2019.

On 20th September 2019, he rejoined Woking joining on a three month loan deal.. This was extended until the end of the 2019/20 season on 31st January 2020. He is also part of the coaching team at Future Foundaiton Elite owned by Dan Goffin

Released by Chelmsford in May, on 2nd July 2020, Loza returned to Norfolk and signed for King's Lynn Town. He returned to Woking on 19th December 2020 after he made it clear he was "unhappy" at Kings Lynn. He had scored four goals in 11 games for Ian Culverhouse's team, twice in a 3-2 win over Woking and another brace in the 2-0 win at Barnet.

He moved to Barnet on 1st July 2022. He was released by Barnet on 5th May 2023, having made just one appearance for them in the FA Trophy. During the 2022/23 season, he spent time on loan with Dartford (one month from 30th January 2023) and Cheshunt (March 2023 to the end of the season), He played four games for each side.

He signed for Southern League side Leiston on 24th July 2023 after a successful trial.

In September 2023 it was reported that Loza appeared at Norwich Crown Court charged with converting criminal property, namely about £27,000, between January and February this year, and possession of criminal property, namely £645 in cash, on August 17, 2022.onverting criminal property, namely about £27,000, between January and February this year, and possession of criminal property, namely £645 in cash, on August 17, 2022. He appeared alongside his co-defendant Lydia Punchard, 23, who has been charged with supplying a psychoactive substance, namely nitrous oxide - or 'laughing gas' - to another between February and August 2022.