Henderson has been named in the Lotto-Belisol team to contest the world's greatest cycle race, which starts on July 1 (NZ time) in the Belgian city of Liege.
The former Dunedin rider, who is now based in Spain, has endured a frustrating couple of years when he was expected to be picked to ride in the tour but lost out in the final selection.
But he left the British-based Team Sky outfit at the end of last season and joined the Lotto-Belisol team, a Belgian-sponsored outfit, which is led by ace German rider Andre Greipel.
Greipel is a world-class sprinter, and Henderson (35) will, in effect, be his wing man, leading the German out of the bunch in the sprint to the finish.
Chris Henderson, Greg's brother, said Greg was thrilled to be selected and race in the classic.
He had just finished training at high altitude and had teamed up with Greipel to help the German win a one-day event on Monday.
Henderson said his brother was in great form and was looking very, very strong.
The Henderson family had bought televisions for bedrooms and there were some long nights ahead next month, he said.
Greipel (29) had a high opinion of Henderson and wanted him in the team to help him in the sprint finishes in the tour, Chris said.
Greipel won a stage in last year's tour and should be a contender for stage wins again this year. He has been in hot form this year, winning 19 races.
Greg Henderson had been in contention to ride the tour for the last few years but had lost out, sometimes due to cycling politics and other riders winning favour because of their nationality.
Henderson told Road Cycling, an online New Zealand cycling website, he was "cherry ripe" for the tour and it was now just a matter of fine-tuning for the race.
He would contest a race in the Netherlands next week to help prepare for the tour.
Henderson's role in the race would be to stay near the front in the stage, and with a few hundred metres to the finish line, find Greipel and drag him up to contest the sprint to the finish.
Chris Henderson said the role meant his brother was unlikely to contest the finish of a stage, but if he could not find Greipel, he might be required to race for his team instead.
Each team has nine members, with most having specific roles to get Greipel in contention.
There is doubt over whether fellow New Zealander Julian Dean will make the starting line for the event after he broke his leg earlier this season.
Hayden Roulston has been picked for the pre-selection list for the Radio Shack-Nissan Trek team, which will be shortened in the next few days.
The tour, which is in its 99th year, has 20 stages, covers 3497km, and finishes in Paris on July 23.
Just under a week after the end of the tour is the road race at the London Olympics.
Chris Henderson said his brother was keen to ride at London, as it was a sprinter's course, which should suit his riding.
The two-man New Zealand team has yet to be selected.
