The 29-year-old was also called up to the national squad a year ago for a T20 game against Sri Lanka but did not make it onto the park.
Malan, who was born in England but grew up in South Africa and went to school in Cape Town, admits he never thought he would get another chance to play international cricket again.
Speaking to Sky Sports, Malan said: "It's always a great honour (to be called up), and I hope I can get a chance this time.
"It was fantastic to get the news. It's hard to describe the feeling you get when you get a call you're not expecting saying you're part of an international squad.
"My ambition, my dream is to play for England. So I hope I can get the cap this time.
"I definitely thought I'd missed the boat - being involved, not playing, and then not being involved in anything after that."
The second T20I will be played on Friday at Taunton while the third and final game of the series is on Sunday in Cardiff.
AB de Villiers (captain, Titans), Farhaan Behardien (Titans), Reeza Hendricks (Highveld Lions), Imran Tahir (Dolphins), David Miller (Knights), Morne Morkel (Titans), Chris Morris (Titans), Mangaliso Mosehle (Highveld Lions), Wayne Parnell (Cape Cobras), Dane Paterson (Cape Cobras), Andile Phehlukwayo (Dolphins), Dwaine Pretorius (Highveld Lions), Tabraiz Shamsi (Titans), Jon-Jon Smuts (Warriors)
Sam Billings (Kent), Jos Buttler (Lancashire), Mason Crane (Hampshire), Tom Curran (Surrey), Liam Dawson (Hampshire), Alex Hales (Nottinghamshire), Chris Jordan (Sussex), Liam Livingstone (Lancashire), Dawid Malan (Middlesex), Eoin Morgan (Middlesex/captain), Liam Plunkett (Yorkshire), Jason Roy (Surrey), David Willey (Yorkshire)
In squad but not available for all the series:
Jonathan Bairstow (Yorkshire) - Available for the first two matches
Craig Overton (Somerset) - Available for the last two matches
Mark Wood (Durham) - Available for the first match
England v South Africa T20s:
Wednesday, June 21, Rose Bowl - 19:30
Friday, June 23, County Ground - 18:00
Sunday, June 25, Sophia Gardens - 15:30