In his home debut against Sheffield Wednesday on 15 December, he again came on as a substitute in the second half and scored a 90th-minute winner, his first senior goal in a 2–1 victory for Crystal Palace.

He finished that campaign having featured in 25 games, earning him a call up to the Republic of Ireland Under-17's squad and was named Palace's Young Player of the Year in 2008.

Scannell signed the contract at the beginning of the new year, and celebrated by scoring Palace's second goal in a 3–0 victory against Wolverhampton Wanderers the following weekend.

The reports stated that Scannell who was linked with the Terriers in January 2012, had agreed a three-year deal for an undisclosed fee and would move subject to a medical.

[9] On 19 July 2018, Scannell signed for League One club Bradford City on an initial two-year deal for an undisclosed fee.

[13] Scannell's debut season with Grimsby was hit by a string of injuries for Ian Holloway's side, this limited him to 13 appearances in all competitions without scoring.

[22] As Scannell was born in England and is of Irish and Jamaican heritage, he is eligible to play international football for four national teams.

[26][27] His good form with Palace led to him being recognised for the Republic of Ireland senior team by coach Giovanni Trapattoni, who called Scannell into his 28-man squad for friendlies against Serbia and Colombia in 2008.

[28][29] In May 2018, it was reported that Scannell had submitted the required paperwork to FIFA to declare for Northern Ireland and would be involved in the squad's upcoming Nations League campaign.