First-half tries from Dave McSharry and Fetu'u Vainikolo set the home side on their way, before Tiernan O'Halloran, George Naoupu and Ronan Loughney crossed after the break.
Leinster meanwhile could only manage two penalties from the boot of Ian Madigan as they fell to a first defeat since their opening loss to the Scarlets - and Schmidt is well-aware of the work that needs to be done ahead of the visit of Munster to the Aviva Stadium next Saturday.
He said: "Preparation equals performance. Ours wasn't perfect and losing players to injury didn't help, but we were out-passioned and Connacht deserved their win.
"It's a super night for Connacht and just reward for Eric Elwood and his crew. They've worked hard and (our former prop) Nathan White will have enjoyed that tonight, captaining Connacht to victory.
"We were not as accurate as we needed to be. Our lack of fluidity is evident in our performances so far. The rebuilding starts on Monday and we have a full week to work into the Munster game."
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