The twelfth season premiered in the UK between January 12 to March 21, 2006 on Cbeebies. In the US, the twelfth season premiered between September 2 to October 28, 2006 on PBS and debuted on Sprout in 2007.
| || Episode|
US title (bottom)
|Dizzy discovers there are bats living in the watermill and she cannot wait to meet them at night.
|"Lofty the Star"|
|The machines build a bunkhouse for Farmer Pickles' sunflower pickers and Lofty gets the chance to show off his talents.
|"Sumsy's Willow Tree"|
|The machines chop down a willow tree that's started to topple over and soon discover how useful the woods can be.
|"Slow Down Scrambler!"|
|The machines are working on building a bridge, but Scrambler tries to slow things down by being too hasty.
|"Travis and the Tropical Fruit"|
|Bob and the gang build a pineapple pit to keep Mr. Beasley's fruit crop warm, and Travis has to fetch a load of manure.
|"Scoop the Teacher"|
|The team are building a bakery for Mr. Sabatini and Scoop is asked to tutor young Benny.
|Bob and the Gang help build a windmill for Mr. Sabitini.
|"Bashing Crashing Benny"|
|Benny is given a new attachment and can't wait to use it, but when he does, he ends up in trouble.
|"Spud's Cork Tree"|
|Spud discovers some cork trees which come in handy when the sunflower oil factory runs out of bottle tops.
|"Bob's Top Team"|
|Bob is busy turning the giant dome into a visitors' centre and learns that his machines can manage without him sometimes.
|"Sumsy and the Beast"|
|After hearing some rustling in the bushes, Sumsy and Spud set out to look for the Beast of Sunflower Valley. Meanwhile, Farmer Pickles' Australian cousin arrives.
|"Listen with Scrambler"|
|Scrambler plays with the children in Sunflower Valley on the last day before they return to school in Bobsville.
|"Roley's Bird's Eye View"|
|Roley would like to get a birds eye view of the valley but is upset that he is too big to reach the top of the observation tower.
|Wendy and Bob announce they are going to fix up a houseboat, and the rest of the team lends a helping hand.
|"Mr. Bentley's Assistant"|
|Mr. Bentley prepares to welcome a group of newcomers to the valley. Spud attempts to help out, but inevitably ends up complicating matters.
|Roley's preparations for a cafe opening are made difficult by some troublesome moles.|
- Farmer Pickles
- Mr. Beasley
- Mr. Bernard Bentley
- Mrs. Barbara Bentley
- Angelo Sabatini
- Sophia Sabatini
- Sandy Beach
- Max (Dizzy's Sleepover)
- Mr. Battersby (Dizzy's Sleepover)
- Baz (Sumsy and the Beast)
- Carlo and Cassia Sabatini (Sir Muck)
|Project: Build It|