The line was closed between Nottingham, Mansfield and Worksop, after the cables were stolen from the Lenton area of Nottingham.
Network Rail engineers have replaced the cable and restored power to the signalling.
Trains will be able to run through the affected area “at caution”.
All trains on the route can now run in both directions between Nottingham and Hucknall.
Trains that have already been diverted will to call at Bulwell, Hucknall and Newstead and will be delayed by up to 15 minutes.
The replacement bus service is still in operation on the Nottingham/Mansfield/Worksop line and will remain in place until 1pm.
Train tickets are also being accepted on the trams between Nottingham and Hucknall until 1pm.
All of trains on the Liverpool Lime Street/Nottingham/Norwich route will no longer be diverted and will now call at Alfreton.
An East Midlands Trains spokesman is warning passengers to check their journey before they travel today.
He added: “East Midlands Trains would like to apologise for any inconvenience this has caused to your journey today.”
For live updates from East Midlands Trains, click here.