The twelfth season premiered in the UK between January 12, 2006 to March 21, 2006 on Cbeebies. In the US, the twelfth season premiered in 2006 on PBS and was also later re-shown on PBS Kids Sprout.
| || Episode|
US title (bottom)
|Dizzy discovers there are bats in the watermill and she cannot wait to meet them.
|"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|