Shadow cabinet: 2008–2015 On 15 January 2008, George was sworn in to a DA seat in the
National Assembly, the lower house of the
South African Parliament. He filled the casual vacancy that arose after
Douglas Gibson resigned from his seat to become an ambassador. George was elected to full terms in the seat in the
April 2009 general election and
May 2014 general election. He was appointed as Shadow Minister of Finance after the 2009 election, in
Atholl Trollip's shadow cabinet, and he retained that position in
Mmusi Maimane's shadow cabinet from 2014. The DA also named him as its constituency contact in Sandton North and
Midrand. In addition, for much of this period Dion served as the DA's federal finance chairperson. He was first elected to that office in 2010 and gained re-election at the party's November 2012 congress,'''''' prevailing in a contest against
Alf Lees. However, when the DA's
next federal congress was called in 2015, George did not stand for re-election; instead, Lees was elected to succeed him at the conference in May 2015. On 1 June 2015, George resigned his seat in the National Assembly, ceding it to
Brandon Topham.
David Maynier took over his portfolio in the shadow cabinet.
National Council of Provinces: 2018–2019 After his resignation, George returned to his private-sector career in finance.'''''' However, he reverted to politics before the end of that parliamentary term. In April 2018, he attended the DA's federal congress, where he was elected to return as federal finance chairperson, defeating Alf Lees's re-election bid. Thereafter, on 15 November 2018, he was sworn in to a seat in the upper house of Parliament, the
National Council of Provinces, where he filled a casual vacancy in the DA caucus. and he also served as the DA's constituency contact in
Knysna. He retained his position as DA federal finance chairperson, gaining re-election uncontested at the party's federal congresses in
October 2020 and April 2023. == National executive ==