The mayor spoke after mounting speculation that the Government aims to hive off control of the eight historic parks. "We don't want them without the money," he said. "This can't be budget dumping on the people of London. We will have to watch that very carefully.
"But there are huge advantages from a democratic, accountability point of view. We would love to help with the parks. We see synergies and ways in which a much closer relationship could be valuable."
Johnson, speaking at the unveiling of public realm works in east London, would not be drawn on how he would run the parks or whether he would create a trust. "We are mindful parks are very political. People care about them very much," he said.
Parks consultant Alan Barber said: "Johnson is right to be nervous. Successive ministers have shown no real interest in Royal Parks except as a source of savings. The big question is how safe are the parks with the culture department?
"Where will Johnson save money, given the Department for Culture, Media and Sport (DCMS) has pushed the parks to raise income but cut grants? The mayor's office has no real experience in park management. London County Council was the great parks authority.
"On the other hand, his office may offer better protection than the DCMS. Johnson has some understanding of the public realm and the real value to London of these crown jewels."
Parks consultant Sid Sullivan added: "If he gets the parks I can see him setting up a committee or board of the great and the good with internal experts. But what are his plans for external experts and will there be a balance?"
He also wondered how Johnson would bring transparency and public-sector accountability to a "fairly closed Civil Service organisation".
"The mayor has pumped in money to parks and has reasonable environmental policies," said Sullivan. "But parks have high recognition value. What will he do that's different? What will he bring that other players don't bring?"
THE ROYAL PARKS
Total size 2,023ha
In-house staff Around 120
DCMS funding £19.4m
Self generated £12.9m
Visitors per year 37 million
THE GREAT OUTDOORS
Two public-realm projects have formed the latest part of a huge landscape-led move to smarten up neglected corners of the capital, spearheaded by London mayor Boris Johnson.
He said Gants Hill in Redbridge, east London, was one of 86 projects in his Great Outdoors initiative to redesign areas and plant 10,000 trees by 2012. "We are doing this in difficult financial times not because we want attractive, beautiful places but because it makes economic sense," he said of the £7m scheme.
The area was improved with new lights, pedestrian and cycle crossings and pavements. Trees will be planted later this month. "This is not just a roundabout, it's the rejuvenation and recovery of Gants Hill," added the mayor.
Nearby Fairlop Waters Country Park was one of 10 parks to receive £400,000. Paths were wrapped around nine man-made rocks for climbing. "These enormous, elephantine boulders will allow children to rediscover sensible risk-taking," said Johnson.
Council leader Keith Prince said: "These improvements have transformed the area, making it more appealing for visitors."