Her most notable theatre credits include Meg Giry in the West End production of Love Never Dies and Maria von Trapp in Andrew Lloyd Webber's revival of The Sound of Music at the London Palladium.

[5] It was announced on 4 January 2008 that Strallen would take over the role of "Maria" from Connie Fisher in Andrew Lloyd Webber's West End revival of The Sound of Music, starting from 26 February 2008.

[6] As part of a publicity campaign, some months earlier on 2 October 2007, Strallen had been "planted" in the soap opera Hollyoaks as character Summer Shaw.

[10] Strallen was cast as Meg Giry in the sequel to Phantom of the Opera called Love Never Dies, from February 2010 to March 2011 in the West End at the Adelphi Theatre.

[16] Interview with Summer Strallen (Dale Tremont in Top Hat)[17] For this role she earned her fourth Olivier Award nomination.

Strallen voiced the part of "Princess Lucy" in The Big Knights, a British animated children and adult’s television series.

[citation needed] Summer played the role of Nancy Morrell in BBC One's World War Two drama Land Girls broadcast in September 2009.