The home side side started the game strongly and took the lead in the seventh minute when Tebogo Potsane found the back of the net, scoring from a rebound after Amakhois goalkeeper Brandon Petersen has initially kept out an effort from Manelisi Mazibuko.
Siwelele then doubled their lead after 26 minutes when Sphesihle Jeza scored his first senior professional goal, squeezing his shot away after being under pressure from Aden McCarthy and Petersen.
The Bloemfontein-based outfit went into the halftime break fully deserving of their advantage and had creating a few more half-chances before the teams went into the dressing room.
Chiefs were much-improved coming out after the interval and had an opportunity to pull one back but home keeper Ricardo Goss denied Wandile Duba.
Amakhosi then missed another gilt-edged opportunity late on when Miguel headed wide with the goal at his mercy as Siwelele held on to take maximum points.
The result saw Siwelele rise to ninth place on the log, now just three points off the top half in the league standings.
Chiefs, meanwhile, remain in third place - five points clear of AmaZulu in the race for a slot in next season's CAF Confederation Cup.
Mamelodi Sundowns moved back to the top of the Betway Premiership after grinding out a hard-fought 1-0 victory over Polokwane City at Seshego Stadium on Wednesday night, edging ahead of Orlando Pirates in the title race.
Kaizer Chiefs defender Thabiso Monyane says his teammates are motivated to end their season with maximum points.
Polokwane City head coach Phuti Mohafe is confident of a result against Mamelodi Sundowns in the Betway Premiership on Wednesday.
Durban City goalkeeper Ayanda Mtshali says he will call time on his career at the end of the current Betway Premiership season.
