Chelsea are a point ahead of Manchester City in the English Women's Super League after a 2-0 win over London City Lionesses at Stamford Bridge on Saturday.
Summer signing Carpenter, 25, scored her first goal for the Blues since moving from Lyon after six minutes, finishing at the back post from Sandy Baltimore's low cross.
A tight battle followed but Kerr wrapped up three points in stoppage time with a brilliant, instinctive finish to capitalise on a mistake at the back.
Kerr is still on her way back to full fitness after a lengthy absence with an ACL injury and has featured only in patches for her club, but at 32 her goalscoring instincts are undimmed.
She played for 70 minutes for the Matildas in Tuesday's 3-0 defeat by England at Derby, having completed 66 minutes in the 2-1 victory over Wales three days earlier.
The legendary Aussie striker ran out to a warm applause at the Bridge when she came on for Carpenter and capped her performance by lobbing goalkeeper Elene Lete.
Sonia Bompastor's side remain unbeaten at the top of the table with six league wins so far and they stay one point ahead of Manchester City, who beat West Ham 1-0.
Aoba Fujino opened the scoring for City in the 26th minute and they nearly had a second when Gracie Prior hit the crossbar after the break.
Victory extends City's winning run to six straight WSL games, while West Ham stay bottom of the table without a point.
