Kapp, who starred in Friday’s eliminator victory over Birmingham Phoenix, took centre stage again at Lord’s, striking 26 off 14 balls before taking 4-9 in her side’s 48-run win over Southern Brave.
Victory meant South African duo Van Niekerk and Kapp, who were married in 2018, have won the Kia Super League, the Australian Women’s Big Bash League and The Hundred as team-mates.
Van Niekerk said: “She’s been incredible. I think I’ve said it a couple of times now, she’s a player for the big moments and I’m just very pleased for her.
“I said I’m probably the most proud, or the proudest person in this stadium at the moment. She was out with an injury for a little bit in the tournament and to come back and make such an impact just shows you the quality of the player she is and she’s the most hard-working person I know.
“I was just so proud of her, she’s so humble.”
Southern Brave had gone into the final as favourites having lost just one match in the tournament, but they were bowled out for just 73 when chasing 122 to win.
Kapp removed top three Danni Wyatt, Sophia Dunkley and Gaby Lewis all for ducks as Brave collapsed to 14 for six, then took a catch before rounding off the tournament with the winning wicket.
That came after her and Van Niekerk had both top-scored with 26 while Fran Wilson scored 25 as the Invincibles batted first.
Brave captain Anya Shrubsole said: “It goes without saying it was obviously disappointing. It’s a shame that the worst game we played was in the final.
“It was obviously really disappointing, a huge amount of credit has to go to Dane (Van Niekerk) and the Oval Invincibles.
“I thought they obviously bowled really well up the top there and you’re going to struggle to chase many things down when you’re three down inside 10 balls.”
James Vince always suspected Southern Brave would be able to withstand a whirlwind innings from Liam Livingstone as they became the first men’s champions after defeating Birmingham Phoenix.
The inaugural edition of the 100-ball competition went out with a thriller as Paul Stirling’s aggressive 61 from 36 deliveries allied to Ross Whiteley’s 44 off only 19 propelled the Brave to 168-5.
Livingstone was the obvious danger in the chase having ushered the Phoenix into the final with 92 not out from 40 balls earlier in the week, while last month he registered the fastest international century by an England batsman.
He threatened to play the decisive hand here as well, crashing four sixes and as many fours in a captivating 19-ball 46, only to be short of his crease coming back for a second run following Tim David’s throw from the boundary.
Having shared 55 in 25 balls alongside Moeen Ali, who made 36 off 30 before holing out later on, Livingstone’s downfall was ultimately the game’s defining moment as the Phoenix ran out of steam to finish on 136-5.
Brave captain Vince said: “It helped that we were bowling second and had runs on the board because we knew Liam and Mo had to sustain the hitting for a long period of time.
“As good a form as Liam is in, we always felt we were only one wicket away. They had to keep going so we were going to get opportunities. Then the partnership got broken in a fairly unusual way with a great bit of fielding.
“It feels pretty good to be crowned champions. Ross Whiteley whenever he’s been called upon has been outstanding – he changed the game from looking at 140 to suddenly 160-odd – that made a massive difference.”