Born in Gateshead, Tyne and Wear, Magnay was the winner of the second series of the Sky One talent search Football Icon.

[2][3] Prior to this Magnay was part of Leeds United's academy and also played part-time for Birtley Town and Esh Winning.

[4][5][2] Magnay's father was the secretary at Birtley Town and he received a phone call from Sky explaining that they were looking for players to take part.

[2] On 30 July 2007, ChelseaTV Online conducted an interview with Magnay, where it was revealed he had signed professional forms with the club.

[12] On 16 June 2011, it was announced that Magnay had been released by Chelsea having made no senior appearances in a spell plagued by injury.

[22] On 15 July 2014, Magnay signed for Conference Premier side Grimsby Town on a one-year contract.

[24] On 1 June 2015, Magnay joined Hartlepool United after a successful spell at Grimsby where he helped his team finish third in the Conference Premier.

[25][26] On 5 September 2015, Magnay was accused of spitting at a spectator after receiving a red card in a defeat to Wycombe Wanderers.

[32] In March 2018, Magnay made headlines when scored a goal from 40-yards for Hartlepool on live TV in a relegation battle against Barrow.

[35] Bates said of the appointment: "Carl (Magnay) hasn't done anything wrong but I spoke to him during the summer and made it clear it was nothing against him but told him I was looking to bring in someone with more experience.

On 7 January 2022, Magnay re-signed for National League North side Gateshead on a short-term contract until the end of the 2021–22 season making the switch back to full-time football.

[40] Magnay played in the 2023 FA Trophy final for Gateshead at Wembley, but lost 1–0 to FC Halifax Town.

[42] On 28 November 2023, Magnay decided to retire from professional football following a long term injury sustained in training.

[45] In September 2019, Magnay began working for his former club Chelsea as a youth talent scout in the north of England.

[47] On 14 June 2024, Magnay joined his former manager Mike Williamson as a first-team coach at League Two club Milton Keynes Dons.